I don't think this is right.

There are certainly prime gaps that exceed 600. In fact, the higher you up (in the number line), the higher these prime gaps tend to get.

http://en.wikipedia.org/wiki/Prime_gap

What's being said here is that despite of that, there will always be prime gaps smaller than 600. No matter how high you go, you can always find a pair of primes that are separated by less than 600. In other words, pick the biggest N you can ever dream of, and there will exist primes p1 and p2 such that they are both bigger than N and their difference is smaller than 600.