DCD985 noise?

[mpc1209]

Hey everyone 

Just a quick(ish) question, I'm an apprentice electrician (as of Sept. 2011) and at Christmas 2011, my dad got me a DeWalt DCD985. I also have just been given a £100 Black & Decker Li-ion combi drill as a cheap substitute for me to use on the work site which has a 3 year Argos warranty including accidental damage/loss as well as the B&D standard warranty. I've not used my DeWalt all too often although quite a few people have borrowed it on the odd occasion - mainly using it to cut holes in metal (e.g. Distribution boards & sheet roofing). I took my B&D drill today and fetched back my DeWalt back home and when I got it out to check over, I noticed there was a slight rubbing noise that sounded like it was coming from the motor. I was wondering if anyone could tell me if this is a problem. I initially thought that because hole saws are high stress for a drill that it wore something out but I'd just like some feedback please 

Thanks, Adam