A little surface rust is not really a problem, especially after only a single outing. The black oxide coated bolts tend to do that very quickly.

The next time you do some maintainence on your bow or the next time you get it wet, remove the screws and coat the threads with string wax or anti-seize compound. That should keep them from rusting in place. As far as the rust on the bolt heads, you could try and coat the heads with a VERY light coating of machine oil or WD-40.

Do not spray the bolts while they are still attached to the bow, you will get far more lubricant on than you need or want.