I don't know how mineral spirits (ms) could get into the lens w/o being put there or the bottle tipped over onto the lens.

SEND IT IN for a CLA....QUICKLY.
And tell the tech what happened so he knows what to deal with.

As was mentioned the big danger is that the ms could have dissolved the grease and relocated it somewhere else in the lens where it should not be, like between the lens elements or into the aperture blades.