It's really cute and funny - he will say "Papa pinching beku" and then I should give him my elbow and he will grit his teeth and start pinching my elbows :-) and take his excess love out. If he is really excited and happy - I should offer both my hands!
A quick googling for pinchers turned up some results where the babies at this age do pinch - and its not so uncommon - but more out of frustration and anger. Mine doesn't really do it when he is frustrated or angry - then he just throws a tantrum and bawls.
I guess it will pass and is just another phase of growing up. But all-in-all - it's really cute watching him pinch away!
Incidentally, it's quite amazing too to see how kids pick-up their parent's OCDs :-) - I have a long-time habit that when I wear socks, I fold over the top portion of the sock where the elastic band would be... primarily so that I don't get those tight elastic marks around my leg. So as a matter of routine, when I put socks on my son's feet getting him ready for school, I did the same. This happened a couple of times. After that I was surprised to see that he was demanding that they be always folded over - from me in case I forgot and from my wife too - who couldn't figure out where he picked this funny habit from!