Rear wheel squeak

I have a 2009Toyota RAV 4 with just over 60K miles.
About a month ago, I had new rear brakes installed.
About a week ago I noticed a squeak coming from the right rear side when backing up - no, I was going slow enough I didn’t need to use brakes, and once going forward the squeak continued for less than a 1/4 mile, then stopped. It only happens when I first drive the car for the day. Does not do it any other time, and especially NOT when braking. the temps have been under 40 degrees lately, but car is parked under cover.
does anyone have any idea what may be the cause…before I take the car to a repair shop…

Take it back and have them check if a brake pad drag reducing clip is missing.

https://www.rockauto.com/en/catalog/toyota,2009,rav4,3.5l+v6,1442959,brake+&+wheel+hub,brake+pad+drag+reduction+clip,18789

Tester

Thank you, very much appreciated.

Tester
It appears it will be a few days before there is an available opening at dealership for me to take my car in.
how serious, dangerous is it to drive my car, if in fact as you say, the brake pad drag reduction clip is missing?
thank you in advance.

The clips are there to pull the brake pads away from the rotor.

This only means the brakes may squeak, scrape, or grind if they’re missing.

Nothing dangerous.

Tester