I think Redneck may be onto something. If the barrel and/or receiver have canted threads, the barreled action may be crooked enough to do exactly what you're seeing. Do what he said and slowly rotate the barreled action, holding the end of the barrel with one hand and the end of the open bolt with the other. You'll be able to see wobble at the barrel/receiver junction if the alignment is crooked.
IMHO, that gun needs to go back to Kimber along with a full description of your findings. If they try to blow you off, persist until they address the problem.
DF
