Thanks, plisar...this is calming! Is anyone else out there who can confirm this is the case at other schools as well?
I understood the deadline to mean all docs should be received by that date, and I can verify that everything was delivered to the proper address or was submitted online in time, but I didn't consider the part where the school has to open and file the transcripts, GRE scores, etc...
When a school says it's my responsibility to make sure everything's received by the deadline, they're not expecting me to factor in their envelope-opening, document-matching time, are they?