your risk for contracting HIV is as close to 0% as any medical risk can be. HIV must be spread through direct contact with infected blood or sexual fluids: these do not include saliva. even if you both had a cut on your lips, a cut isn't simply sufficient, it would have to be fresh and bleeding. outside of wet bodily fluids, HIV does not survive very long at all.
so take a few deep breaths, relax, and don't worry, you're HIV free.
if that doesn't convince you then you can always get tested- you have to wait at least 3 months before you do so to ensure a correct test- but really, you have nothing to worry about.
hope that helps