I noticed some irritated spots on my 1 year olds back. They look like a rash. Doesn't bother him. What could it be?

Lots of things. Rashes, spots require a visual exam because they are hard to diagnose without seeing them. It could be a virus, or bug bites or reaction to a zipper or snaps, etc.
Agree. But regardless of the cause, if it's not bothering the child, and if the child is otherwise healthy, it's probably transient and not significant and you can afford to watch and see if it goes away on it's own. If it bothers your child it should be evaluated by your doctor quickly.