Spurious "send reply with a new subject?" warning

Hi, I'm pretty sure this is a bug and not something I screwed up myself. I just replied to an email and got the "Do you want to send a reply with a new subject?" dialog even though I had not touched the subject line. (See attached for a screenshot of the warning.) Obviously this is a minor issue and not cramping my style too much, but figured you might want to know anyway.

The original subject line contained some special characters (a slash and an ampersand), so my educated guess is some kind of minor issue with those characters tripping up your regular expressions or whatever heuristics you're using to detect changed subject lines?

PS, I'm fairly new to MailMate but loving it so far... extremely minor (and understandable) bugs like this aside, it's a huge improvement over my previous mail client, Postbox... Postbox had most of the special features I was looking for in a pro-level email app, but the downside was huge issues with reliability. Thus far, MailMate has been rock-solid, so thanks for that. (And FWIW, MailMate does most of those advanced features better than Postbox did, to boot.)

Cheers,
Matt