Latest OTA on mine, though I do use Go Contacts and Dialer. Not sure if that would somehow be causing it. I'll check a few other things, see what I can manage. Also not rooted on my end. Will report back in a few.
EDIT:
Ok, I got mine to do it (at least for the moment). Though I use Go Contacts, it wouldn't change, even after telling it to only show Google contacts. However, going into the People app (stock contacts), and doing the same there and clicking done at the bottom, it apparently saves for both apps, and now, in either one, if I go to add a new contact, it defaults to Google properly.
Yay!
So, if you're using another contacts app, make sure to try to change it in the stock one as well, to make sure it comes through, see if that helps. Now I just have to move the last 5 that I apparently had in the phone, over to G, and I'll be set.