Leaking toilet

Hi, We have a 2021 Venture Sonic 190vrb. We have the regular type of toilet with a pedal to flush. Every so often clean water leaks out. It is very slow and only happens occasionally. I’ve checked the fresh water connection in the back but it’s tight and I can’t feel water around the fittings. I don’t know what else to check….
It’s definitely clean water so the seal at the bottom is not the issue I think. 
Any ideas would be greatly appreciated.

Thomas