2
Not all modules do the best job of cleaning up after themselves.
If you are worried, it is always best to check after an uninstall to make certain your DB is in good shape.
btw. Contact Us was not rewritten for this version (so far as I can tell...) So whatever problem is there, has likely been there for awhile.
Pax vobiscum,
...mark
may the road rise to meet your feet!
http://treemagic.org