It's not desensitization at all, I think, or if it is, it's only in part. Think about smoked cheese for a minute. It's good, from the first day, but wait a couple weeks and...
Besides, when I do the smoking, Redhot notices the same thing, and vice versa.
Hell, I even noticed it with some pulled pork we bought at Bob Gibson's to bring home after our last visit to Decatur. I've been disappointed with Gibsons the last few times we've had it over the years, but that was eating it the day it was cooked. This last trip, we got a big order (Hey, my mom was paying so if you're wondering why when we aren't that enthused...) to bring back, mostly for the smoked turkey (Which is quite good, by the way). First night we were again disappointed. Not much smoke flavor at all. The next day though, it was a transformation from meh to DAMN! Had to rethink my opinion a bit.