The problem I'm having is an inability to cut and paste from employer provided info... They'd get upset about that. But I've seen text from GE that says what I'm saying... I'm pretty certain they called it "Bowed Rotor effect" (the flippin' things shake and shiver while they find their happy place) and it's cause is said to be inadequate cool down.
I've heard/felt it many a time during many starts... And, I've also seen, many a time, when I give the poor dears their twenty minutes at idle after a hard run... the next start is as smooth as a baby's bum.