HELP - bike handle bars shake like crazy

Everyone,

So I did my second sprint triathlon yesterday (it went well by the way). The bike course was all paved, but in sections the road was terribly bumpy. Like shake you off your bike bumpy. I had to slow down a bit to navigate for fear of losing control. It was only really bad for a mile or two I'd guess, but perhaps half the course was more bumpy than I'm used to (I tend to ride on nice smooth ashpalt paved streets around town).

But anyways, I noticed something during the bumpy portions, my handle bars would shake like crazy. No problem when I had both hands on the hoods, but as soon as I went one handed to get a drink, the side that I let go of would start vibrating and shaking, to the point where it would make lots of rattling noises and I'd feel it in my other hand. It wasn't a chip seal road, but I'd imagine that I would have the same problem on chip seal.

So I guess I'm just wondering if this is normal. My bike is a brand new Specialized Allez Elite, bought from a good LBS in the area, so I assume it was assembled correctly. I've "inspected" the fork and head tube to look for anything loose and I don't see anything that seems like it would indicate a problem, but I'm no bike mechanic for sure. So it's left me a bit concerned. Any suggestions or comments would be appreciated!!

Thanks,
Mike