Most Helpful Girl
As long as your both legal, that's fine. She may be okay with that too. For some odd reason I've always been into guys two years younger than me. I can't explain it. If you like her, go for it.
Most Helpful Guy
Like what everyone else said, it's ok as long you are comfortable with it. when you two get older, the gap of 4 years will not make a difference. Good luck, man.