Thank you all for the advice. If it puts your mind at ease, these are circulating coins that I'm collecting, so the gentle wipe with the old shirt is probably the best treatments they have had in years. That being said, advice taken acetone soaks only.
My main point in asking the question is is this small invisible residue on the coin cause for concern for the future? If a coin that has this residue on it but is then rehoused in a new flip in a pvc free album - will it continue to deteriorate or will it be fine?
I only ask this because I have spent a couple days rehousing my old coins from their damaged flips, if it turns out I need to take them all out again and do the acetone soak I might lose it but oh well.