It may need an adjustment, usually a pretty simple procedure. However, before adjusting, make sure the wheel is completely seated in the fork dropouts. I like to loosen the quick connect lever, stand over the bike, push on the center part of the handlebars with one hand and engage the locking lever with the other. Many newer bikes have lawyer tabs on the fork, so make sure you're clear of these.

If that doesn't do it, it sounds like an adjustment is in order. Search the appropriate web site to obtain directions. Various disc brakes have different adjustment requirements.