The main reason I bring it up is because as he is getting faster it seems to be getting more pronounced. The 2007 and earlier videos of him I have aren’t nearly as good as the HD quality ones from the last two years due to youtube upgrading, however it definitely does not seem to be as prevalent then as it is now.
I don’t think excessive head sway is a good thing. Getting better while your mechanics get worse is called pulling a Gatlin. I would say he normally looks pretty good though.