Is it any and every photo? It could just be the angle. Some babies (especially those with Asian heritage - I don't know if this applies to yours) can have quite a broad, flat bridge of the nose and pronounced folds (epicanthal folds) of skin in the corners of their eyes, producing an effect known as pseudostrabismus - in other words, one eye (or both) appears to be 'wandering', when in actual fact they are fine. As a photo is just a split second snapshot, it's possible that you're capturing moments where the white of his eye becomes reduced by an epicanthal fold.
Also, have a look at where the light reflects off his eyes in the photos. There should be a small white spot of light in the same place in each eye. It's called the Hirschberg test - if you put it into Google images it might be easier to understand. If you notice that the spots are in different places, that could well mean his eyes are misaligned.