Why is my corn so unusually small?

I hate to add to the flood of "how old is my corn" type posts, but all the discussion lately about size and age has got me worried about my own corn. I received my snake (a male normal motley) in mid-March. I stupidly forgot to ask the breeder how old he was, but I assumed he was an '03 because the rest of the animals for sale were. He was about 12 inches long when I got him, and was an established feeder.

I fed him one pinky a week until the end of May; since then I've been giving him two pinkies a week and just recently moved him up to fuzzies. He's been shedding like clockwork every 45 days, and seems perfectly healthy.

The problem is that he's only 17 inches long right now. Everyone else's yearlings (such as in this thread )seem to be well over two feet long. Why is mine so small? Is it possible that he could be a freakishly early '04? Or have I been feeding him too little and stunted his growth?