What is wrong with my AC+ Control in white. Weird dirty spots NOT CAUSED by me appear on my pad.

Hello guys, basically the title.
I get these random dirty spots appear on my mousepad (they start to disappear a little bit but won’t disappear completly). I ordered 2 same pads just different sizes, one is okay and the other one (mine) has this problem. I’m 99% sure that I did not do it myself – I’m taking extra caution because it’s white. I even tried to wash it – didn’t help, it’s still there.
When I opened it for the first time it had 2 little dirty spots but I thought I’m just gonna wash it and it’s going to be okay but no, washing doesn’t help at all and I can tell you I tried hard. 
It looks like a wet spot but it’s not. 
Does anyone have same problems? 
link for reddit, there are pictures so you can see I can’t upload it here (don’t know why) : https://www.reddit.com/r/MouseReview/comments/l9zp52/what_is_wrong_with_my_ac_control_in_white/