You are probably right, David, since a true belly pan would be made of aluminum or steel. The scraping sound sure gets my attention though, and it prevented me from trashing the car too much when I inadvertently ran over a parking lot beam that I didn't know existed. But then again, maybe it wasn't high enough to do any real damage...
...still, it does hide small leaks that may go undetected if you're not the type to peek in the engine compartment now and them.
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car