...and DEL to BOM this morning on 6E - checked in online, only hand baggage. I asked the Indigo lady whether I'd need a stamp and she said no, and that was fine.

The only quirk was that the security goon at DEL demanded to see "ID proof" in addition to my boarding pass, which had never happened before. Not a problem in itself, except that my passport was in my coat pocket, and the coat was going through the x-ray machine. Had to go and fetch it while he held back the security queue, waiting for me...