If your unsure of the inspection date and the time of the last virgin left in the hive to mate, all bets are off of what happened in that hive.
She might've took off like a rocket after your last inspection (like apis says, a young or freshly mated queen can be a world class sprinter and it's real easy to miss a patch of eggs). With the early winter weather we had and right amount of stores, she could've been laying into mid October or later. Better check on their cupboards, if they're light because that happened, they could easily starve in March.