Does he still want her?

ok, so.. my boyfriend is a fireman, and he was a a floater meaning he was at different stations every shift.. he wanted to go to a certain station for good. he didnt want me going to take him dinner or anything saying that its a waste of time and gas.. before he was with me, he hooked up with a girl, who so happens to be at that same exact station.. he and i have been together a year and a half.. now dont get me wrong i know it was before me, but now i fell like i have to worry. he says he didnt like her, shes annoying, we dont even talk.. he must have liked her to be with her. he says to me it was 1 time and i love you, your all i want.. should i be worried? im just wondering, if he still likes her.. i dont want to feel like i am in competition.