Haha, yeah that is a 2x4. Should I do something about it? Doesn't seem like a problem...

 

Really as long as it's securely held in place it should be fine.
I once had a K10 pickup hit a pot hole in the road, battery came loose and went forward touching both terminals to the radiator support, shorted everything out, fuses, even killed the engine.

 

I also used a 2x4 to hold my battery down for quite some time, worked great and was very secure.