Well, she made it through a cold spell in January, a long, sudden cold snap of about 10°F at the end of February, and several hard frosts through the whole month of March. Now she's pushing buds. It seems 7(a) is tolerable for this little Live Oak.
I’m in 7(a), so a little bit colder. The seedling was growing strong over the summer. Hopefully, I won’t see dieback as a result of the Christmas Cold Snap. It definitely damaged the leaves, but live oaks shed their leaves every spring anyway. The seller noted on the website that the seedling might have some escarpment live oak genetics mixed in, and those are supposed to be a bit more cold hardy, if I recall correctly.