Replying to Jealous

i dont know why, but i always seem to get jealous when my gf pays attention or gives compliments to other guys. for example, this guy commented one of her myspace pics saying something like "damn u sexy girl," you know, the typical comment that objectifies girls, that has become oh so common. now i guess im pretty protective of her too, so i go and check out his profile and i look at one of his pics to see a comment from her saying that it is "the hottest picture ever." Is it wrong of me to be jealous over something like this? like i kinda want to say something to her but i dont know if i should make a big deal out of it or not