Michael,
I do see important event "NSM-4-IFDOWN" which basically means that port is shutdown and that is why AP goes into reboot.
There is good minute and half gap between first and second PD signature in above log, which means AP boots and operates for certain amount of time.
I do wonder if there is any configuration present on affected APs.
Are those getting adopted when booting or are those standalone?
Also, are every time
same APs showing the problem? Different ports on switch?
I do smell hardware issue here...
Regards,
Ondrej