Noise When Reversing

Hi all, long time no post from Texas. My 2005 automatic 330i ZHP sedan just hit 130,000 miles on my home from work today which is pretty cool. Within the last few days it has begun to make a weird grinding type noise when reversing and going forward for a few miles after initial start-up. After a few miles it is fine and there is no noise when stopping and restarting after being warm. I found on a forum someone with what sounded as similar issue to mine which I posted below in quotes. Have any of you encountered this and could it be something different? If it is indeed the wear sensor am I doing further harm by continuing to drive with it loose? Any guidance much appreciated.

"Brake wear sensor had come lose, and was getting stuck between the brake caliper and wheel rim."

hmmmm, if brake wear sensor comes loose, you could try putting it back in its spot.
Do you have a brake warning light on in the cluster?
It is such a small piece of metal that I have a hard seeing this causing a "grinding" sound.
But I could be wrong and will let others chime in.