Jon was using an Elecraft K3 at 100 watts on 20m with a vertical antenna. The recording was made on 27 May at 0713Z.
The delay was 1.272 seconds.
(UPDATE: As Sverre mentions in the comments, it is meaningless to attribute this degree of accuracy to a transceiver - after all, it is not a piece of test equipment. So let's assume a 1.2 second delay).
This delay is too long to be explained by normal long-path propagation of his own signal back to him - over 10x too long.
Jon shared an MP3 file of one of the examples. I opened the file in Audacity so that it could be seen visually and so that cursors could be placed in order to measure the
Sverre LA3ZA explains part of the delay here.
But still - almost 1.3 seconds is a very long delay, even when factoring in sidetone/RF transmission timing differences + receive processing time + LP propagation. The sum total should amount to far less than 150mS.....