A Petty Studio Productions website shows a date that confirms Panic Button was recorded in very early July, 1960 (this site is off by a couple of days). I am confused by how this site uses dates. What do you think about it? You likely uncovered this site when you were researching PSP.
For Panic Button, 7/4/1960 is shown, but not described as "unreleased" or "released". I assume this is the session date and Glen could have been on this session after meeting up with The Champs a few months earlier. Big assumption: Glen might have been filling in for one of group members on this particular session.
See: http://www.superoldies.com/pettystudios/a-f.html" onclick="window.open(this.href);return false; (control-F and use search word "champs" to find this record).
At the top of this webpage is info that might be of help with regard to the missing session information in PSP's files:
Just my two cents: I believe the guitar playing on "Panic Button" has a young Glen Campbell "Buzz Saw" / "Buzz Saw Twist" sound.Petty productions not issued in the USA are noted.
Some of these may have just used Petty's publishing concerns, but were recorded elsewhere.
Dates are based on disc reviews and label information by [month / day / year].
Master number(s) are used for identifying records with no assigned number.
Reference to unissued material is drawn from articles, liner notes, surviving acetates or direct from the artist.
There could be other discs by virtually all the artists listed.