Should i let my girlfiend hang out with my bestest friend?

So me and my girlfriend have been together for a lil over 4 months. We both love each other very much. So after we been going out she has been texting my best friend and hanging out with him practically every day im at work. They always text, hang out and go out to lunch. What should i do, yes it bothers me a whole lot, and i hope there not doing anything. Should i even be worrying about whats going on?