floor bubble - not sure why...

[lspajm]

has anyone had this issue -- I have a 2011 Passport 3220BH -- in the bathroom right inside the outside door and in front o the toilet the floor (which is a solid piece of vinyl throught the camper) - has a bubble in it -- and when you walk in it you can push it down, but then it pops back up.

Now i know -- everyone will say -- your sink, toilet, shower are leaking..well..they are not -- i have done several things while camping and the water is on (city water), as well as while it is parked -- and nothing is leaking --- so why the bubble in the floor??

And....how can I fix it since when they make these things I know what they do -- roll out 1 large piece and thne place all the walls and cabinets on top of it...

Thank you for any help!!!!