You must be mixing up some notes. There were no small size $20 red seals issued. Only green $20 Federal Reserve Notes. Only $1, $2, $5 and $100 small size legal tenders with red seals and serial numbers were printed. If it truly was a red $20, then it could be an overprint error. The only other ones like that are two $5 bills, each worth over $100,000.
More likely a Hawaii note. Those are brown seals, but they seem to get called "red" fairly often by non-collectors....
Found a bunch of 20's in AU condition from 1934, also 15 consecutive number 100's from 1934 in Unc. condition, they smelled like cedar wood, took a few weeks letting them air out but if you have a good nose you could still smell the cedar. I kept one 20. and one 100. for my own collection as I dont save or hoard anything, traded off a lot of them for other notes I need for the collection but still have six 100's left and four 20's to trade. Regards Bill Collector
i read somewhere that there were $10 and $20 red seal notes being printed, and $50 and $500 notes planned but not in production, in the early 1960's, but they were supposed to all be shredded and if exist would be illegal to own. not sure what the series date on these would be, but it would be cool if someone found one
If I recall correctly the BEP displayed a sheet of $20 red seal star notes at a show and do so periodically.
Kennedy was a big proponent of having USN red seal notes made for circulation and was not fond of Federal Reserve Notes so what you say is not surprising to read. After Kennedy's demise, red seals were doomed and were ultimately entirely replaced by FRNs.