The possibility, however remote, exists that you will randomly select a sequence with patterns and order. In cryptography, we define the term 'pseudorandom' in order to discuss a class of functions that look random. Pseudorandom sequences are sequences where, given the first n bytes of the sequence, an adversary cannot guess the n+1th byte with probability significantly higher than 1/2. Basically, it's important to distinguish between blindly selecting a sequence out of all possible sequences, and finding a particular sequence with no discernible internal order.