Is there more than 1 data point than of the OP being refused to illustrate a change in practice (as opposed to a newbie on the line going by the book)? Obviously it was never an official benefit of concierge tier but they did it anyway, granted I only availed of this on a couple of occasions myself but it was also always done without any problem.
You always get the odd person not recognising that maybe a bit of flexibility for high status pax is fine, I once got told at the check in desk in ORD when I asked for an aisle seat further forward in Y that there was some available but I'd have to pay for it, tried to explain that this usually was not the case but met with a blank stare and just chalked it down to wrong person wrong time. I would have been more bothered about it subsequently but I got bumped to business at the gate so happy days.