I don't see that quote, do you?
I have found a youtube video where 1 minute into it, Patrick talks about it being very difficult keeping jennifer focused ie laughing, giggling, crying... but it worked.
http://www.youtube.com/watch?v=b3Oc6PeTk9A
The I found this article:
“Patrick Swayze memoir recalls Jennifer Grey as a pain on set of ‘Dirty Dancing’”
http://community.livejournal.com/ohnotheydidnt/39475258.html
If that does not satisfy you... sorry... I made my point and grey’s actions on DWS backs up my claim.
LLS