What they *should* be doing is cutting out the bad area and seam welding in a patch. They can order from the factory or if small enough, sometimes you can steal a piece from an inconspicuous spot inside a cabinet or another hidden spot.
Before you let the dealer fix it, I would discuss it with the guy who would be doing it. They need to know how to do it. Ask if they can show you something they've done on another unit. If you don't trust them, find a professional floor layer to do it. Properly done, you'll have to look pretty closely to see the repair. Regretfully, some dealers are good at some things. You want it fixed right the first time and you also want to make sure there's not defective sheet flooring elsewhere. I know 100% for certain that our dealer can do this properly.
The flooring is not glued down. It's free-floating and is stapled around the entire perimeter of your TT and then they build everything on top of it. If it's bubbling up for no reason at all, that's not a good sign. Vinyl sheet flooring sometimes does not do well in cold temps. but it would be damage from shrinkage. Bubbling would suggest expansion from heat, not cold. Maybe there is something else going on underneath.
The most important thing to address is whether or not it's due to water leakage somewhere. If not attended to, water leakage can cause major damage. I would get it looked at asap.
Finding things that need fixing is more the norm than the exception. Just make sure you deal with things under warranty that need to be. Sometimes little things can be easier to repair yourself. Maybe posting a pic. would help.
