I've been having problems with my Dragon subscription too. It started with issue 306. Before issue 306, every issue arrived like clockwork, during the first week of the month. I was kind of surprised that, living in Japan, I was getting my copy before many subscribers in the States. Now I have to e-mail Paizo every month in order to get my copy. I haven't received issue 314 yet. Strangely enough, I'm not having any problem getting my issues of Dungeon.
The folks at Paizo have been very apologetic, and have sent me the issues, but I shouldn't have to e-mail them every month. I wonder how many subscribers are having this kind of problem.