CentOS - Sep 2009 - squirrelmail and pam tally and invalid imap logon attempts

Greetings,

In trying to use pam tally to secure pam-aware services from brute
force attempts, it worked well for all but one aspect.  It seems like
a client using our Squirrelmail setup creates an invalid imap login
attempt every time they refresh a webpage.

Has anyone else experienced this or have a clue why SM does this?