Apple //gs Easter Egg - maybe

[xenman2@aol.com (Xenman2)]

I have had a ROM 01 //gs for a number of months now and the other night I
switched it on with no drive to boot so the normal 'Check startup' warning
came on.  Having a baby in one needing feeding, I left the computer in
that state while I gave baby her bottle and watched TV.  I really lost
track of time, but when I looked at the computer screen later,  it had a
credit listing of people apparently responsible for the ROM programming. 
Pressing a key sent the gs into the monitor with a hexdump and I could not
do anything without shutting down.  I have not been able to duplicate this
event, only having retried twice.

Is this an Easter Egg and when is this event supposed to occur?