2003 Hyundai Tiburon front struts

I was at a Canadian tire 2 weeks ago and he wanted to replace my front struts . I told told him the front end was just replaced by a very good sh ope. And that insurance paid. I'd think if they felt the struts were going the would have replaced them. I asked him why he thought this and he pointed to a very small patch od dirt and oil right where the top and bottom of shock join. All I know is the car drives great and handel like a dream. What do you think just one more CANADIAN tire story? How can I tell if i need to replace them?.
Thanks