Could very well be a bad wax ring and/or flange under the toilet. This could cause the toilet to leak everytime you flush under the vinyl or tile you have down on the floor and seeping it’s way underneath it towards the door frame. Just a guess. Usually though, you should see some seepage around the base of the toilet, so if you don’t see that at all it could be something else like a pinhole leak in a supply line running up inside the wll near the door frame…..so it will yake a bit of leak detection and troubleshooting to get to the cause of the problem. This could also be happening from a “sweating” toilet tank, in other words a tank that gets filled with very cold water while the ambient air temperature inside your home is much higher causing condensation and the tank to drip water onto the floor… only way to really solve that problem is to install a mixing valve. Hope this helps some.