Don't worry. Do a check from a dink when you are next in a comfy place just to be sure, to be sure.This furniture in a bendy plastic shell has long been a problem. Does the designer
use the furniture to stiffen the hull
(Old Prouts do this with Ply Bulkheads at the front and back of the cabin
, with some cracking seen at the bottom of the door openings in the rear bulkhead) or try to isolate it by either not connecting it at all (an inch gap to the roof) or connecting it soildly in one plan only (i.e. the back, leaving the top and bottom free to move).
will flex, it's how this is handled by the designer
, and your's has gone for tidy joints to the hull which don't transmit any great forces or load the GRP skin unevenly. There are more expensive ways of doing it, but a retro fix might be difficult.