I would think it would be ok for that short amount of time. Can you leave the door open so it can dry/air out? Can you return it?

I've got pets, so leaving to door ajar is a definite no-no.

Not really sure there's reason to return it (the sound fluctuating over the first few days of operation may be normal, for all I know), but I definitely feel concern about leaving it running unattended while there's the possibility of something being wrong.

Turn it off and leave door open while you are still at home. Once it becomes room temperature, wipe it out to dry it. Put an open box of baking soda in it. Close the door. The baking soda will keep it from getting sour while you are gone. When you get back, have it serviced.

The classic RV owner's dilemma. :)

Homechef's method should work.

Or maybe you could put it in a closet while you're away so you can leave the door open?