I use OK google every day during my commute. When it asks me to confirm, I always say "yes, thank you" and it just tells me its doing it. But a couple of months ago it said "you are, of course, as always, very welcome". I was stunned. It had noticed, or it was a human intervention, or they put that in at random every 800 times you ask it to do something, I don't know. It hasn't said it again since.