Hi Jim,
I'm not sure if this will help, but here goes...
I had the same problem on my 2011 XF-S, albeit with the right side calliper. Had them both replaced, plus new pads all round. While that was being done, the indy dealer found that the automatic release for the handbrake on the right hand side wasn't always doing its job.
A liberal soaking with WD40 got it sorted! All has been fine now for over a year!
Cheers,
Jon