It was stated there was a rug there the entire time (1 1/2 years) Moisture doesn't evaporate if it's covered up 24/7, especially if the rug had a rubber backing.
That said, N Hollywood does not seem to me like a place with torrential rains. Cheap laminate on an unsealed concrete slab? ...and no molding on the front door??? Wow, that's tacky.
Is the front door the only place with problems?
How large of an area was covered by rugs?
....and were the area's covered by rugs the only "problem" areas?