New image pulling old information…..?

I got a weird problem... and I mean WEIRD... a while ago when we were doing the monolithic image (maybe... May 2010ish) I built an image off a user's machine that had a bluetooth keyboard and mouse setup. I had forgotten to remove it from the bluetooth device list (so under devices it shows username's keyboard and username's mouse) on every machine that was done with that image. Fast forward to the August build I did w/ instadmg... done off a completely different system, using instaup2date, etc and the OEM dvd's... we just deployed to a brand new out of the box 17" MBP i7 ... and I got a note from the deployment team that the bluetooth devices is populated with that same user's keyboard and mouse.. Sure enough, I just checked my system, which I deployed this same image on a week or so ago, that same devices are populated. That user sits in a physically different building - so it's not like I can pick up the Bluetooth signal from it... Any idea's how or why it would pick up the information from a system 3+ months ago?