Bolt working up thru floor

[gll]

We just bought a 2010 Cougar 292rks 5th wheel and once we got it home we had a bolt sticking up under the Linoleum flooring, it was not there when we bought it, I gently cut the floor and its a fine thread 1/4 in bolt with a phillips taper head, I tighten it down and use a little wood glue, next trip when we arived home its starting to stick up again, this time I used lock tite thread locker and put it back down, any one know what its for or why it would work its self up in a short 80 mile pull ? its located about center of the Rv, a little forward of the axle and center of the room.