I've never seen or heard of this happening but I just had a BP lose a spur...He was a CL pickup(got him a few weeks ago) that was in pretty bad shape..scale rot and such..cleared up the scale rot, he shed, ate VERY aggressively(he's now one of my best feeders), and now I'm handling him 2 weeks later and his spur just comes off...anyone ever hear of anything like this happening??