The floating liner is typical in a yard with poor drainage or in areas with a high water table. I have very good drainage but still get a little float about once a year during heavy rain. The water will seep back down after the ground dries and the liner typically goes back into place.

Getting the liner back in the track may be a bigger challenge depending on the age of the liner. They stretch much better when they're new. I've drained a couple feet of water from mine to get enough flexibility to reattach the liner in the past.