After using our shower (located one floor directly above our water heater/utility room) it seems to cause the hot water pipes(?) to emit a very high pitched squeaky, almost ringing sound. It goes away eventually, and resumes after using the shower again. Is there some connection not tight enough, and the pipe is rubbing against itself? It shakes only slightly & doesnt seem to be hitting any other pipes, etc. Any help would be appreciated, the sound is driving us nuts! Thanks.