What would cause this? (Claying)

[mills3]

Hi everyone. I have a question about what would cause this discoloration on my clay, but first let me explain the vehicle. Today I washed, clayed, and waxed an mid 2000s Ford Excursion. The paint appeared to be in pretty decent shape. As I was claying I was constantly getting this really "sandy" feeling as it was gliding across the paint. I understand that's what it was supposed to do, but when I looked at the clay, it was this weird green color. 30422
As you can see, the paint was like a tan or beige color. 30423

Can you tell me what would cause this? Was it a problem with the clay, or just that much dirt and grime on the paint?

[Setec Astronomy]

It's probably just dirt and grime. It's also possible that there was some paint overspray on the surface that was a "weird green color".

[GettingStarted]

Overspray would be my guess.

[cagui1223]

My money is on green overspray. I recently detailed my fathers camper and had to wetsand the beige surface to remove all the bonded contaminants. When I lifted the 1500 grit sandpaper I noticed it was blue. As it turns out the lower area of the camper was resprayed blue and they did a terrible at covering up the surrounding area.
After a compound and polish, everything was as good as new.

[mills3]

Thanks for the replys everyone. I had no idea what that was.