have you tried washing it off? If you don't have a record wash machine (eg VPI 16.5) there are manual methods.
In any event, this sounds like a good reason to toss the AQ mat and get another type - like the Funk Achromat which does not leave any residue, and works wonderfully (I have no financial interest in Funk - just like the mats).
In any event, this sounds like a good reason to toss the AQ mat and get another type - like the Funk Achromat which does not leave any residue, and works wonderfully (I have no financial interest in Funk - just like the mats).