Yeah, I see. It IS probably just due to a curve in his shinbone from being squished up in the womb. Babies can be in really random positions in there. Mine, for example, was 8 lb 15 oz, so pretty massive, yet I am not a big person at all and was absolutely enormous bump-wise by the time I went into labour. Most of my labour was posterior (back-to-back) too, which just goes to show in my opinion that she was cramped and in a crappy position in there.
After birth, her right side was all scrunched up with the arm bent and turned in and her head turned mostly to the left - she actually favoured her left hand for the longest time, which worried me so much too, but she did even out in the end. Looking back on it, I think she was just in a bad position in there due to being just too big for me. I think her right arm and leg were maybe squashed in with her left free to wave and explore. All theory of course, but it makes sense to me, and would explain why her left hand was stronger and her favourite pretty much from birth. She still uses it more now, but I think she is actually right-handed as she will usually choose the right hand for tasks that I, as a right-handed adult, would choose my own right for.
At the time though, of course, I worried she had something like cerebral palsy, which wasn't fun at all for anyone involved. She doesn't have it.
We took her to a cranial osteopath to be 'corrected' when she was very little and were able to learn a lot about her body and the many discomforts she was experiencing from her birth. It was fascinating and I would highly recommend it. Her neck was stiff and hurting, but three ludicrously gentle treatments sorted it out.
Anyway, sorry for going on again. This is all just so interesting to me. Your LO is stupidly cute by the way!