They have Agreeable Gray in a prepackaged option which is great for touch up. 

It's an old post, so OP probably isn't still around.I might touch up the paint if the house settled and had cracks that needed repair.

Now that it is painted in our color schemes, it should be simply touch ups going forward. 

Some long timer posters are probably going to cringe when they read this but I prefer to let the unit go vacant so that I can turn on the utilities in my name and do all the repairs and touch-ups needed to make the unit show well.

Our plan of attack is to just drive by on days it snows first thing in the morning for a quick inspection and touch up if needed (and repeat at the end of the day if it has continued to snow).

This is the same reason most builders tell you not to paint during year 1, since they won't touch up paint that they didn't put on the walls. 

To our surprise, during the due diligence period we were allowed to enter the the property and it was in fantastic shape, built in 2008 with modern finishings, no structural issues, and very light cosmetic touchups needed.There was existing month to month tenants paying only $1,100 / month.

If it is just a couple chips in the drywall and scuffs on the wall, I'd charge for the drywall repair and the touch-up painting. 

We only have 5 original interiors left to rehab and then some exterior touch ups, add some amenities and stripe/seal the parking lot, re-branding and landscaping.

Maybe offer the girlfriend $ 100 to really clean the place and touch up any marred places on the wall, so that it'll be ready for showing.