21 Prime click noise at accelerating

Tried searching. no luck

Obviously I am not new to "strange noises" from Prius
I am new to the 21 Prime though.

I have noticed over the last couple weeks that when I am accelerating I hear a strange click,
just one time when I hit 14-15-16 mph from a power on.
I do not believe it happens from every stop. Just a cold start
Hard to get it with kids in or other things happening, but when I drive solo on sat/wed mornings
I am by myself and I do not use radio etc.

I did definitely hear it, as I was ears open this morning.
and at 14 hitting 15mph it happened.

It is a single click, sounds like a relay of sorts.
I do not think it is suspension or mechanical
windows were up with AC on but low demand (so quiet)

Any clue what this could be?

I have only had a chance to hear it about 5 times or so, so far.

 

The noise maker is not part of the click sound and it (acoustic thing) goes on and on until ~25 mph

However, it may be part of the electronics for it?

idk, but this is not threatening me in any way, just has me curious enough if other people notice it.