I've use to cut the lid of a plastic container into a 2" x 2" square and gently scrape off an residue. If it's finished as you say, just take your time.
You could try a WARM hairdryer along with the scraper if the residue is really persistant. DON'T use HOT air as you may do more harm than good.
If you want to wait a couple of days, maybe Henry in MI can offer his expertise in this area. My best to ya and hope this helps.
PS: Maybe hot water on a damp rag???
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