Hmmm I never thought of it like that, I have reinstalled Oblivion about 6 times since starting my mod and the same error has always been present. I really hope there is no problems with Pell's Gate (the mod) as that would put two years work down the drain.
Nah, unless you do something
really stupid (something you can't really do by accident) you can always clean the mod with TESEdit. I don't even think the error is problematic, but personally I feel bad when I get an error in one of my mods and can't get rid of it. Had that in my Sheogorad mod once, but fortunately I found the reason why it came up and could clean it with TESEdit. It wouldn't have caused any serious trouble, but I'm still glad it is gone. I sleep better that way.
If you don't care about the error just leave it like it is, you can always try to get rid of it before you release the mod. If it doesn't go away it won't cause any problems either I'm sure. Except maybe a very minor performance hit, but nothing that would make a noticeable difference.