It's a bug from converting the forums from phpBB to SMF. The post's from previous forum times have that problem, haven't noticed it happening with post made now (after that conversion).
Other than that the conversion went successfully so I didn't bother looking for workaround since it's not very major bug, and there weren't that many posts from the old forum anyway.
test anyway:
solidus/
uppercomma'
Thanks for pointing it out.