Is this an abnormal rate of spoke breakage?
Yes, as the comments pointed out, this is abnormal.

I would make the attempt to take the wheel back to the LBS where you bought the bike. The might be able to work with Specialized and get the wheel replaced completely. Once at the LBS, have the mechanic inspect for any external factors (derailleur strikes, etc).

If they can't get it replaced, then I would either: (1) have the wheel completely rebuilt replacing at a minimum the spokes but taking a good look at the rim once it's disassembled...as noted in the comments, it might be warped; or (2) buy a new wheel. Having it rebuilt can often be pretty pricey and you can get a decent wheel these days for a couple hundred.