Depending on where you're at and the water/air temps you could be getting condensation on the inside of the hull.
Also the cockpit lockers drain into the bilge. I know if I get a hard driving rain I'll sometimes get some water in the port locker but I'll be damned if I can figure out how it gets in.
95 Catalina 30 Island Time
“If a man is to be obsessed by something, I suppose a boat is as good as anything, perhaps a bit better than most" - E.B. White