Not that it’s on par with the Great Quiz Show Scandal of 1959 or the Great Bobby Ewing Death Hoax on “Dallas,” but Fox’s count of episodes of “The Simpsons” seems to be a little bit … suspicious. The network has been touting tomorrow’s new episode, “Don’t Fear the Roofer” as the animated sitcom’s milestone 350th. But as some hard-core “Simpson”-ites have taken the trouble to point out, the numbers don’t quite square. What’s up? A little May-sweeps math? A Fox representative said it is definitely No. 350. But if you go to the official episode guide and count forward from the similarly ballyhooed 300th episode, then tomorrow’s installment is No. 349. On the other hand, if you count from the very beginning of the series, the episode Fox labeled the “300th” appears to have been the 302nd, which would make tomorrow’s episode No. 351. Maybe they’ll get it right with the 400th.