They should be in the freezer. The colder you keep something the less it degrades.
Did he technically lose some potency ?
Sure...technically, is it significant in the slightest ? No not really.
The doses we tend to consider normal are a bit on the higher end to begin with and the degrading in an air conditioned post office for a few days is so minimal...a little off the top of a compound already hitting that diminishing returns barrier is not a big deal at all.