A Headache From Shopping?

I can't believe that I actually got a headache from shopping about a month ago!  I just remembered it while I was looking at posts on my blog.  At the time maybe it was because of all the people that happened to be in the store that day.  But someone did suggest that maybe it was because I was under a lot of stress?  Well, after I got home I took some aspirin and I feel a whole lot better!  Of course I have been shopping since then (gotta eat!) and it hasn't happened since.