linguistic oddity

For the past year, I've been noticing a new phenomenon among English speakers: when pausing and thinking anxiously, they fill the pause by saying ch-chch-chch-ch... it's like they are singing a beat.
I interpret it as saying: "I don't wish to be interrupted, and will come back to you in just a moment", and can be used while thinking or while driving.

I have observed this in at least 25/M/Canadian, 30/F/Canadian, but I suspect it's widespread in the USA too.

Is this a new phenomenon?