I still, on occasion, get xp for going to a place for the first time, when in fact i've been there a number of times. Most notably, its happened on the thin road two or three times.

It's possible that the resref of the area got changed at some point, due to it being redesigned or something similar. If you consistently get XP when entering a particular area, please send us an exploit report (don't post it here); otherwise, don't worry about it.