I recently went on a two week business trip, then 4 weeks of vacation. I never thought about leaving my smart unused (until I read this thread...) for that short of a period. When I got home, I drove off with no issues.
Four years ago I quit my job and traveled around the world for a year. I drove my Honda into a storage unit when I left, disconnected the battery and shut the door. Upon returning, I charged the battery and drove off. I still have the Honda, and while I did have to replace that battery a short time after I got it out of storage, there have been no other issues....
For several weeks of non-use on a modern car, don't give it a second thought.
geosynch