Should I be concerned that my son doesn't appear to walk properly?

[Currie30]

My 23 month old son has no difficulty getting about but he hops, runs, jumps or skips everywhere. On the very rare occassions that he does walk he appears to have a very slight limp. His left shoe is always much more scruffed than his right. He is very happy and healthy although he was born 2 months early and is still catching up. He is small for his age.