nope, doesn't blow any smoke.
1) am i correct in assuming that the purpose of brake cleaner is to clean that crap off the exhaust headers?
2) what am i looking for after the 100 miles, to see if it happens again?
A solution of simple green may work also to remove the "stain" I'd try that and then look again as suggested. I thought you'd be seeing it smoke also. I was thinking new piston rings initially. I am no mech. though.
Might try checking the torque on bolts there also? Be interested to hear your findings.