site still works without mysql gem installed

Like many people out there who work with Apache and Mongrel cluster, I
had the problem where the Mogrel servers die after a period of
inactivity.

I found out this is due to problem with the mysql gem, thus I
uninstalled the mysql gem. The strange thing is that the website is
still working without the mysql gem. How can that be?! (I did not freeze
the gems)

Rails bundles the pure ruby mysql library in case you don't have the gem...