Exhaust smoke on start up

[St. Louis Boxster]

I've got an 04 Box, not an S, and after the car sits in the garage for a couple of days I get a significant amount of smoke out of the exhaust on start up. It goes away quickly, like by the time I back up into the street. The oil level is fine, the car has 8K miles. Recent;y 2 months ago, I had a seal replaced on the rear end that was causing some oil drips on the floor.

Any Boxter forensics out there?