[JRTJH]

The vinyl flooring is not "glued to the subfloor under it. The only adhesive is around the perimeter to hold the flooring in place until the trailer is constructed. That is "by design" and not a "skipped step". The flooring, if it were glued to the subfloor, would expand/contract at a different rate than the underlaying structure. That would lead to cracks in the winter and buckling in the spring. Take a look at your floor and see if you can identify something near the bulge that could have been "pushed toward the bulge before it was installed permanently. You might find something like a floor heat vent that's just slightly larger than the hole cut in the vinyl. When the vent is pushed into the hole, it makes the vinyl floor bulge slightly where it's pushed away from the hole. That's just one example of a possible cause for the bulge.