Fine ABS residue on PEI Textured Plate

I've been printing copies of the same 3 boxes in multiple colors of ABS for my classroom Just now when I went to run an emergency Silk PLA print (mailbox numbers, yay mailbox randomly falling over!) I noticed there was a very fine (can only see when the light hits it right) residue in the shapes of the boxes on the plate. Assuming I get through the PLA print, what's the best way to remove this fine residue or is it time to order a new plate? One side of the plate does not want anything to stick but this side has been rock solid.

I let the ABS prints cool to room before I take them off the plate and they just lift off so I don't know where thie residue is coming from. Do I wash with Dawn, use IPA, acetone, what?

Qidi Q2 with the stock plate that it came with. Stock formware, it's airgapped.

Thanks!