That's an interesting one. I'd email that to the help desk at [email protected] to let them know about it. If there's some kind of cause of it that would be helpful for others to know, it'd be great if you could post more information back on this thread.

Another advantage of not having a technology extension is that if you change technologies and go from .html to .asp, you don't have to change all of your URLs and worry about redirects and lost link juice.