A high number of comments might indicate that the code is well-documented and organized, and could be a sign of a helpful and disciplined development team.
Ideally I would like that to also say "a low number of comments might indicate that the code is readable enough that it doesn't need them" ;-)...
Seriously though, every comment I write is a red flag for me. I don't like it when I'm doing something that isn't clear from the code itself, so if I catch myself trying to explain or make excuses I stop and think hard. Sometimes there's no way out, of course, but I think this counts for something too.
See also an interesting post on the subject by Aristotle Pagaltzis, which seems to share my sentiments in a more articulate manner.
In short, I've tried very hard to make my comment count low (no boilerplate, and fewer situations that need comments, I just have them when it's necessary or when I feel really witty), and I don't think that it merits a warning sign.