The bolts are just that - a bolt and a nut. if they in backwards you should be able to simply loosen them and insert them the other way. You may have to take some weight off the suspension with your jack (on the frame rail) however as I expect without doing this the holes will become misaligned with the trucks weight on the springs. Best bet if you aren't comfortable with doing it/don't have the time, etc - take it back and have them make it right.
If this is indeed your problem you should see where the bolts have the paint rubbed off the frame. I don't see how they would contact the frame as the hangers are welded to the frame and move with it - not towards it. The bolt heads on mine are on the outside - nuts inside.
Here is a pic of the hanger wand how it is welded to the frame. I don't see how orientation of the bolts should matter as the hanger and frame don't move independent of each other. Everything I have saw has the bolt head outside - opposite of what SETaco has said?