I am familiar with that noise. I try to find the sweet spot on the pedal to make the noise last as long as I can to bug my wife when she's in the car.
If you can, turn regen down to low, then go hit some backroads to do a few HARD 60-0 stops in a safe desolate place. 3 in a row, with a minute of cooling in between. That will ensure the pads can really "wear-in" to the rotors again and clean them up, since they were crusty beforehand.
I like to heat up my brakes a few times a week just to make sure they're being used. My mobile tech said he has never seen rotors so clean on a car with almost 40K, and I've never had the brake maintenance done. If you use them, they will remain in great shape. Exercising the calipers often is really helpful for the brakes.