Just a quick one here. On getting my 3yr old out of her seat(behind passenger) I noticed a pool of water in that little cubby hole at the side of her seat nearest the window. Now I can't be 100% that it's from my daughters beaker of water but IF it's not where has it come from & how do I stop it from happening again. No windows were partially open and can't see any wet patches to show where it may of come from?? 