I really have no problem there ... I've been playing fretless for about thirty years now, and fretted a bit longer than that. The fretless experience could have something to do with it. You know we all have our weak points and strong points, intonation for me is a strong point. The fretless bass that I used the Sharpie on is a Conklin GT-7, and my weak point is that when I switch to my fretted BDGT-7, the string spacing is different, and I have to really stay conscious of it or I'll screw up! You know when your reall y goin' and working with a drummer with eye contact and the sweat is flyin' and then all of a sudden for a split second I'm inbetween strings! Intonation is a strong point of mine, always has been. You know, were all different.