If the PEM certificate associated with an identity expires the IRC server will not automatically identify the nick. (Guess how I found out!)
Add a message box warning the user that their certificate expires in under 3 months so they have time to update & upload a new one.
This is an RFC: Is this the best way/place to add such a check? Also, I appreciate the 3 months lookahead is pretty crude. If this feature seems like something that would be useful I'll update the patch based on any feedback.