I haven't noticed any particularly obvious lateness in any of the half dozen or so Marvel titles I collect, at least not in the last few months. However, with respect to trade paperpacks and hardcovers, things have been somewhat more spotty.
In order to check whether the problem is with Marvel or with Westfield, what I would do is check the recent Diamond shipping lists to see what has actually come out. Here's the URL :
http://www.diamondcomics.com/shipping.asp
Besides giving lists for this week and next, they have an archive of lists going all the way back to 1998. Looking at some of the recent lists, it looks like the last X-Men related hardcover that was shipped was the Ultimate X-Men, vol. 1, which came out Aug. 7.