(and several other posts along similar lines)

If anyone thinks hotels change their rates just because they booked something, they have a highly inflated idea of their importance to hotel revenue management software.

I know a good deal about that sort of thing, having published several papers and a couple of textbooks on decision-support and decision-making software. While it may seem odd that (a) happened right after (b), that does not prove that (b) caused (a). In this case, I can assure you that it almost certainly did not. In fact, if there was any connection between the two events, it would be in the other direction: the software would see that fewer rooms remained and would raise, not lower, the rates on the remaining ones. If the rates went down, it was for some other reason - such as there not being as many bookings within a certain time frame as would normally be expected - despite (not because of!!) yours.

Bottom line: you did NOT cause the rate drop. They are NOT out to get you. They did NOT try to get you. Relax. Chill.