I comment on all posts, especially if I can help (even to clarify).
Gotcha - that makes sense... and I've had that happen on other cars, but it was more a function of a weak retractor (due to dirt, debris, etc).
It's definitely a crap design (snaps and a strap, rather than a smooth plastic loop). There was a TSB for the retractor, which you can ask your dealership about. Also, since it's seat belt related, you MAY have some pull with them since seat belts are a 10-year warranty item... Worth a try.
The couple G vert owners I know of have said they have the same issue, but they have gotten in the habit of manually feeding the belt back into the slot. I had to do this with my S13 droptop as well. Considering neither car was designed to be a convertible in the first place, it's kind of a halfassed design to stay in compliance.
I'd try the dealer route - you may have to pitch a bit of a fit, but worth a shot. Keep us posted.