ML mail.app email addresses overlapping?

Hi,

I recently upgraded to ML and so far, I have only noticed this one small problem. In Mail.app, when viewing a message, the email addresses in the headers sometimes display overlapping one another. In the image below, I have intentionally blurred a couple of email addresses for privacy reasons.

My problem is concerning the overlapping text. It appears that the line starting "Peter,..." is errantly wrapping to the next line and overlapping with the text that should be on the next line. I know that the "...Corporate, Consultant)..." should be part of the "Peter,..." line.

The issue is sporadic and does not happen to all messages. Any ideas on why this could be happening? Perhaps a bug?

Thanks,
Matthew