2008 Panda With Odd Residue

My father in law has this beautiful 2008 Panda that appears to have some sort of residue on it. The case it is in had what looked like small piece of grass or hay inside with the coin. The two spots are where the foreign object was in contact with the coin. I've tried distilled water and acetone to get the coin back to normal with no luck. Do I now consider this a toned coin and let it be or try something else? The coin came in a nice display box as well.