Not sure why but saying 'Ok Google' feels a little creepier than saying 'Ok Glass'. More obvious that you aren't interfacing with a mere gadget, but a multi billion dollar corporate entity...
Contrast this with Apple (Siri) and Microsoft (Cortana?), who do the same thing, but try to make you treat their apps as some kind of human with crude tricks like pre-written jokes and puns. Personally I find that way creepier.