is my jealousy normal?

During the last couple months of my relationship with my boyfriend, I've been getting really annoyed and jealous by other girls. He's a good guy and wouldn't cheat or do anything to harm our relationship. He's just naturally friendly. He's not talking to any, they're friends of his from before we were dating, etc. But there's a couple of girls that constantly tag him in post on social media saying that they miss him and such. That really grinds my gears. I get annoyed whenever he just mentions another girl's name. Is this normal? I feel like I'm irrational about most things and that I'm crazy lol