Looping Delay?

I am a big Pearl Jam fan, especially of guitarist Mike McCready. Anyways, I have a live recording of a performance of 'Daughter' where during the mellow jam session at the end of the song, Mike plays a quick note which repeats itself. Then the repeating tone begins to speed up faster and faster reaching a 'sound peak' (I don't know how else to describe it..) and then trails off into what sounds like modulating feedback. I just wondered.. how does he use the delay to repeat the tone and speed it up, all without going into feedback? I attempted this once with a Roland Analog Delay rack unit, but with the unit set to infinite repeat, the tone always went into feedback... Any ideas?
Thanks!
-Yeabudy-

Could either be that he's turning down the delay time (which would make the pitch rise if it works by increasing the loop speed), or has the pedal just on the brink of self-oscillation.

sounds like the first one dot said.