I experienced something similar but with more drama. I had 2.5 hrs riding on my same-day-new-from-the-dealer F800GS when, as I was completing a slow left turn, the front wheel locked and I went down... maybe 10-15 mph.
My first indication of a problem was while in the left turn lane and I had no front brakes. I did have the rear brake, so I tried to finish the turn to pull over to the side of the road out of traffic. When I touched the rear brake again, the unattached caliper swung forward like a pendulum and jammed between the spokes and the right strut. What followed happened in milliseconds: the wheel locked, the axle snapped and the right strut jammed into the disc. I high-sided and saved the side cases from damage with my foot. No, not intentionally.
(The side cases are missing because I had to leave the bike in the dealers driveway after it was towed.)
A couple good samaritans helped me get the bike up and one found the caliper which had no remnants of the missing bolts, no torn threads... just a snapped brake line. This makes me believe that the bolts left the bike before any of this happened (vs. a bolt snapping).
I've found someone in the UK (UKGSer.com forum) that had a similar but not identical experience. In his case the caliper vibrated badly, so he found the problem without coming off his bike.
The dealer is doing everything I could ask for to get the bike back on the road. Couldn't be happier with their response which included the offer of any bike in the house to ride till mine is street-ready again. They've filed a PUMA and hopefully some light will come of that. The biggest issue is that, being a new bike, there aren't many spares in the US yet. Nearly everything was backordered. They now tell me that they should have the mass of the parts by 20 October.
Santa Fe, NM
ps- this was the best scenario I could have hoped for. About 4 minutes before I was on the freeway doing 75-80 mph. I really don't like to think what that could have lead to!