Most Helpful Guy
No one would get physical with you and dating you for a month, and then react in a way that isn't just absolute happiness when you kiss him.
For me personally, if a girl initiated a kiss with me (assuming we like each other obviously), I'd be the happiest person you can imagine.
If he likes you and gets physical but hasn't kissed you yet, chances are he's afraid of your reaction. Imagine how he would feel when you initiate the kiss.
Most Helpful Girl
If you feel comfortable, go for it! Make sure its right time, right place ie. not in the middle of the school hall way.