Soft floor in 95 Winnebago?

[HarveyP]

We looked at a 95 Vectra yesterday that had a soft floor in living room and kitchen area. A 94 Chieftan on the same lot had the same soft floor. The salesman and service manager claimed that it was a factory issue of shims between the floor and frame that had slipped out of place over time. Their claim was that it was an easy fix, but labor intensive because someone had to crawl into the storage bays and push shims back into place. Is this anything you have heard of, or is it just hot air? Thanks, HarveyP