I recently noticed water collecting next to the tub. After watching closely, I realized it doesn't happen during a shower or bath, and only collects after a shower is complete. At first, we thought that water was seeping in somewhere along spaces in the caulk, so we re-caulked. But it's still happening. The water seems to be starting at top of the tub where I'm pointing to in the picture below. What could be the cause of this?