If you get the password wrong, there's about a half second delay (where the dialog input appears active before you get the 'shudder' effect.) Not sure what it's there for, as unlock happens immediately.
Most likely PAM stuff is happening. Upstream (at least at the start) prints "Checking...". This can be changed in the PAM conversation though. Successful authentication is probably quicker because chances are it is the first method in the stack.
Are you still seeing this Bill?
Nah,better now.