Why did Yaakov only await fulfillment of the *second* dream?

Summary: Perhaps because only celestial bodies bowing goes out of the natural order; or maybe, the purpose is to stress that Yaakov's criticism of the second dream was a sham, to try to keep peace among the brothers.

Post: Rav Yechezkel Avramski writes, on parashat Vayeshev:

"And his father kept the matter in mind: How come only for the second dream did his father keep the matter in mind?

There is to say that in the first dream, in which the sheaves bowed, it was not necessarily so that the dream came to indicate something, for it is not outside the realm of the normal that sheaves fall. However, in the second dream, that the hosts of heaven bowed, this was something which was not normal, and then Yaakov understood that the dream came to show the future, and therefore he kept the matter in mind."

This is a perfectly fine dvar Torah, and I am not coming to knock it. I generally prefer that the question be more compelling than this, which in turn would make the answer more compelling. I think there are more straightforward peshat answers to this question, and which case the answer is random. It might well be true, but it might well not be true. This just arises from a different style of parshanut, I think.

But I like the question, because the straightforward answer can help us understand the (possible) role of this  pasuk in the greater narrative.

Consider the first dream, in 37:7:

'for, behold, we were binding sheaves in the field, and, lo, my sheaf arose, and also stood upright; and, behold, your sheaves came round about, and bowed down to my sheaf.'

It is only the representatives of his brothers who bow. His father does not bow. Furthermore, no mention is made of telling it to his father. Rather, in pasuk 5:

And Joseph dreamed a dream, and he told it to his brethren

Meanwhile, in the second dream, in pasuk 9:

'Behold, I have dreamed yet a dream: and, behold, the sun and the moon and eleven stars bowed down to me.'

By mentioning the moon and sun, this includes his father and mother (or 'mother'). And he relates it to his brothers, in pasuk 9:

And he dreamed yet another dream, and told it to his brethren

and in pasuk 10, he relates it to his father as well as his brothers:

And he told it to his father, and to his brethren

It is admittedly strange that he tells his brothers twice. Maybe one could argue that this relating in pasuk 10 goes on both dreams, or perhaps not. Rashi accounts for the repetition as follows:

10. And he told [it] to his father and to his brothers, and his father rebuked him and said to him, "What is this dream that you have dreamed? Will we come I, your mother, and your brothers to prostrate ourselves to you to the ground?"		י. וַיְסַפֵּר אֶל אָבִיו וְאֶל אֶחָיו וַיִּגְעַר בּוֹ אָבִיו וַיֹּאמֶר לוֹ מָה הַחֲלוֹם הַזֶּה אֲשֶׁר חָלָמְתָּ הֲבוֹא נָבוֹא אֲנִי וְאִמְּךָ וְאַחֶיךָ לְהִשְׁתַּחֲוֹת לְךָ אָרְצָה:
And he told [it] to his father and to his brothers: After he told it to his brothers, he told it again to his father in their presence.		ויספר אל אביו ואל אחיו: לאחר שספר אותו לאחיו חזר וספרו לאביו בפניהם:

If so, perhaps his father would have been שמר את הדבר even for the first dream, except that Yosef never related the dream to him. That would be my first answer.

My second answer would be that it may well have been that Yosef historically related his first dream to his father, and his father believed that dream as well. If so, it is only that the Torah chooses to mention וְאָבִיו שָׁמַר אֶת-הַדָּבָר by the second dream.

Why would this be so? In answer, consider what Rashi says:

his father rebuked him: because he was bringing hatred upon himself.

ויגער בו: לפי שהיה מטיל שנאה עליו:

Yaakov rebuked him not because Yosef was saying impertinent nonsense, but because Yaakov realized the impact such dream-sharing could have. And that is the role of pasuk 11, then:

11. So his brothers envied him, but his father awaited the matter.

יא. וַיְקַנְאוּ בוֹ אֶחָיו וְאָבִיו שָׁמַר אֶת הַדָּבָר:

That is, there was this impact, which Yaakov recognized, of increasing the brothers' jealousy. And know that despite his criticism of the import of the dream in the previous verse, in actuality, וְאָבִיו שָׁמַר אֶת הַדָּבָר, Yaakov believed it to be plausible as a prophetic dream. Thus, it is only because of the criticism of the dream in the previous verse that the Torah deems it necessary to add this statement of Yaakov awaiting the matter.