How young is too young to have an inferiority complex?

My son's teacher told me today that he has been crying at random times pretty much every day. 

I was sad to learn this as he hasn't said anything to me about it. 

He was excited, and maybe a little bit worried, about first grade for most of the summer.  But, I would never have expected that he would be so emotional so early on in the school year.

I sat down with him tonight and talked to him about it.  I wanted to find out what was making him so sad and you know what he said, through his tears.

"Everyone has four pages written in their journal and I only have one.  No matter how hard I try I will never catch up to them."

Seriously....it's 1st grade.

Why is he so worried about what everyone else is doing?  I tried to explain to him that everyone works at their own pace and that one awesome page is just as good as three.  That school is not a contest.  That doing your best is the most important thing.

This did nothing to alleviate his anxiety about being the last person to complete his journal in the entire classroom. 

We've only been in school for two weeks.  He actually had trouble falling to sleep tonight because he "couldn't stop thinking about it."

I'm sitting here wondering what I've done to him to make him feel like he needs to be the fastest and the best all the time?  How can I make this better for him?  Is he always going to be this hard on himself?

Any suggestions?