Actually it is a very obvious mistake. Someone booking for the same day would book the offered AP rate, not a refundable rate when the cut off time was gone. I did not pick the cheapest rate offered; I picked a refundable thinking I may change dates a day or so on my actual visit. Someone booking & going the same day would pick the cheapest rate. Why pick a refundable rate if the cut off time has passed?!
I actually can't figure out how the date change occurred. When I was looking at available rates, AP rates were available. They aren't supposed to be available for same day reservations but if the dates were shifted when I hit the back button BEFORE picking the rate, why was AP still available? Somehow the date change occurred between me picking my rate and the final confirmation page. Which is why I didn't double check dates.

I called the next AM @ 700 EST. It was already too late when I made the booking since the cut off time had passed (no penalty time 1600, res made 1930).
The only one who can make the change is the FD manager who had already left by the time I made the res. I was told he only works until 1700 BST and doesn't work Sundays.