Seek your counsel on my 2008 328i and brake pads.

My warranty and maintenance ran out in February 2012 (extended warranty still good). I bought my CPO BMW in April 2011 with approximately 35k miles on it (current odom is under 52k). On 12/24, my "service engine soon" light on the dash came on. I checked the iDrive control message and the rear brake pads icon had a yellow triangle and "100 miles" under the message. The dealer was closed for the holiday. Over the next 2 days, the "service engine soon" light went off but the control message for the rear pads went red and is now tracking the miles in the negative. I've got an appointment Friday at the dealer and pads and rotors are going to run me $650 + tax. My questions is this: if I bought my BMW CPO, and the rear pads need replacement after about 17k, am I justified in complaining that they should've been replaced during the CPO certification inspection? I've read that any wearable parts on a BMW like wipers, brake pads etc are replaced if they are 60% or less. Keep in mind I drive like an old lady and would definitely not think that I qualify as someone who rides the brakes or does a lot of city driving. The iDrive shows the front pads have 60k miles left (although I'm not sure how accurate or what the standard is for the control messages). Should I ask for my CPO inspection sheet? Or am I just wasting my breath?

Thanks in advance!