How much gas do you think might be left in the hose and plumbing from the previous fueler that might have used 87 octane? Or, are they different pumps?
At quicktrip, the non ethanol pumps have their own handle and are usually red coded. I don't usually get my gas anywhere else unless I'm travelling, but I seem to recall that was the same at a florida chevron station I used. YMMV.