While doing my a 45k oil + filter change and removing the requisite access panel on the 2015 Mazda 3, out plops a white cloth pad with 8 rusty holes. I couldn't tell from where it was once attached. It looks like a heat insulating pad. Should I be concerned or throw it in the trash? Thanks all!

 

I wouldn't worry about it. I don't think it's part of your car to start with.