Trauma related allergies?

Is there such a thing?

I suffered a severe accident back in the late 80's involving my hand, and I'll leave it at that (PTSD never lessens).  Not long after that, I remember waking up in a hospital after having an allergic reaction to eating a hamburger.  I have never been allergic to beef before, so I never made the correlation until my next hamburger.  Is it possible that a traumatic incident could make me allergic to beef (and pork) or an ingredient such as the dye, or is this just a coincidence?