Door will not latch

The door will not close enough for the latch to engage. It has always been tight but now I cannot push hard enough to latch it. There is nothing restricting the door that I can see other than the seal which looks good. The latch does line up side to side with the latch strike plate in the top of the cabinet. Is it possible that the seal has swollen and is now thicker than original? If so, how do I replace the seal? Thanks for your help