Yes this is a common view and some of little soft stones do look a bit like olive oil but I don't think that it is reaction with the ES as you can get the same result by omitting the ES altogether. The old traditional recipes didn't include ES at all because it wasn't available. Good for stimulating conversation and reaffirming faith in flushing.
You may need to review your views about olive oil which if first cold pressed virgin oil is 100% natures own bounty and only the bottle it comes in is man made. Happy grapefruit flushing!