I see what you are saying. It would seem the individual who posted that info had taken actual head clearance measurements. You'd have to take your own measurements to be really sure. Just in case he had an improperly machined head button or something. I'd say if it is running fine, don't worry about it, just keep an eye on the temps and listen for detonation. You'll know when it starts detonating. It will have a distinct crackling noise and performance on the top end will be a bit diminished during all that noise. If the head clearance is in fact higher than typical than you should be fine.