I see you're from Cincinnati, you must of been on the KY side, I get alot of old and proof set coins back for change at gas stations, and speedway is the best 89% of the time I get a proof or pre 1950 coinage back. Must use anything they can get to buy stuff.
People steal proof and mint sets from homes and are too stupid to know what they have. Had a moron years ago walk into my dad's service station and lay out a $20 gold coin for cigarettes. The employee took in the coin and gave them his change because he thought it was just an old coin.