Hi Mike!
   The bulges in the carpet on the walls doesn't necessarily mean a water leak, although, by all means check for that!  It could simply mean that the tacky glue they used to install the carpet is getting weak and coming loose.  After years of temperature fluctuations, dryness then moisture, etc etc, the glue begins to fail.
   Also, it is my experience that there is usually  some staining on the wall and/or carpet, if water is involved.  Just my opinion, for what it's worth, and I've got my fingers crossed it's NOT a leak!  Lol!
Beaver salutations!
:^3=~
Carol