permission denied in edit.php

I converted a phpbb db to punbb with the converters mod - not everything came over for some reason (although there were no errors) but generally I was very pleased.  There was one post whose subject in the forum index view appears to be colored gray.  I'd assumed that was because the user was no longer there but that the post still was for some reason (conversion error?).  I wanted to update the post's subject and when I tried to do so, I received a permission denied error in edit.php - in looking into it further, the user still exists and is not an admin.  I don't know why I couldn't edit the post (being Admin) and just went and edited the sql db directly which worked just fine. 

Is there a reason an Admin can't edit the subject of a new post started by someone else, or is this a bug (or just a problem with my install/db)?  Have I missed something obvious with regard to why the forum index view colored that particular post gray?

Thanks for any help, nothing critical here but it makes me curious.
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Updated: 

Well duh, I locked the thread - that's it was colored gray and that's why I couldn't edit it.  Eesh.  :-)