Glock 23 frame recall

I was looking at a very clean used G23 a few days ago and was about to purchase it when a friend of mine told me some of the older ones had a frame problem that could possibly crack a rear rail. I have not called Glock yet but was wondering if anyone heard of this.

There were some bad frames several years back, as I recall, though I don't remember the details. I'd poke around on www.glocktalk.com to find the serial number range.