Today I spent some time at the beach with my diver, a Seiko SKX. I took it into the ocean several times, and at one point I took it off for a while, and it got pretty hot in the sun. Tonight I was surprised to find that the crown is stuck. I can't unscrew it with my fingers. I'm thinking either that some debris got in there or a gasket deformed from the heat, in any case obstructing the movement of the threads. Any other hypotheses, or suggestions about what to do? I'm thinking of trying to unscrew it with a nylon-tipped pliers.