OK...so I am driving and I hear a mechanical rasping noise from the rear of the car...doesn't sound bad...just like a pebble rolling around on the brake shield or some such.

Well I parked the car immediately and finally got around to looking at it from underneath...bad news and really troubling. one of the bolts (one closet to ground and rear of car) that appears to connect the brake caliper (just a guess from the location and it appears there are maybe 4 of the bolts) bracket to hub (at least from what I can tell from underneath) has mysteriously worked its way loose and was backed out and grinding down the metal serrated wheel speed sensor on the drive shaft at the hub. It is a flanged bolt and the flange kept it in (only partly) but it chewed up the speed sensor ring. I guess I am lucky it didn't catch :-( Now I have to ask the question...this bolt is the only one that appears loose but for the life of me can't imagine it coming out unless it was either not tightened at the factory or someone loosened it...but I do have a jaguar dealer that I won't ever be going back to...

Anyway keep an ear out for this...