you probably didnt heat the grip tape enough I let go back and forth slowly for several minutes with the heat gun and then use a razor blade to lift the edge and then slowly peel up as you hit the top with the heat gun.
@glyphiks WD40 has a majority of a mixture of hydrocarbons what they call aliphatic hydrocarbons it does have some petroleum based oil in it though. A while ago I ran it through our GC/MS system. Before that I was also under the impression that it was an oil.