The Miracle of Chanukkah

This I heard from my father. The miracle of Chanukkah is recorded in the gemara, in Shabbat 21b, as follows:

מאי חנוכה דתנו רבנן בכ"ה בכסליו יומי דחנוכה תמניא אינון דלא למספד בהון ודלא להתענות בהון שכשנכנסו יוונים להיכל טמאו כל השמנים שבהיכל וכשגברה מלכות בית חשמונאי ונצחום בדקו ולא מצאו אלא פך אחד של שמן שהיה מונח בחותמו של כהן גדול ולא היה בו אלא להדליק יום אחד נעשה בו נס והדליקו ממנו שמונה ימים לשנה אחרת קבעום ועשאום ימים טובים בהלל והודאה

In English:

A Cruise of Olive Oil?

What is [the reason of] Hanukkah? For our Rabbis taught: On the twenty-fifth of Kislew²²  [commence] the days of Hanukkah, which are eight on which a lamentation for the dead and fasting are forbidden.²³  For when the Greeks entered the Temple, they defiled all the oils therein, and when the Hasmonean dynasty prevailed against and defeated them, they made search and found only one cruse of oil which lay with the seal of the High Priest,²⁴  but which contained sufficient for one day's lighting only; yet a miracle was wrought therein and they lit [the lamp] therewith for eight days. The following year these [days] were appointed a Festival with [the recital of] Hallel²⁵  and thanksgiving.²⁶

The Greeks made all the oil impure. The one cruse of oil was not impure, since the seal of the Kohen Gadol was still on it, unbroken.

However, the "problem" with this evidence for purity is that the cruse of oil could be rendered impure with maga or masa, touching or carrying. Even if the unbroken seal were upon it, how did they know that it was not impure from masa?

And that is the true miracle of Chanukkah -- that no one thought to ask that question!