2000 Avalon short buzz/vibration only when first moving

[mbrowncog]

I have a 2000 Avalon XLS, 82K miles.

I start the car, put it in reverse to back out of the driveway, put it in drive, and gently push the gas pedal.

There is a short 1 second buzz or vibration from the front end, then it's gone for the rest of the trip.

It does this every time I get in the car and go. Doesn't matter if the car is hot or cold.

I have an excellent mechanic, Toyota certified, and he's stumped. If you have any clue, please let me know - thanks!

[mbrowncog]

UPDATE: It's the ABS system doing a self-check. Totally normal.

[TrailDust]

Thank you for the update....much appreciated!