Hey Trotter,
Yikes! Close call for sure. I've been pelted with a few small rocks, dodged a few bigger ones. But a cantaloupe-sized rock? Yeow...an impact for sure wouldn't have ended well.
Similar story, from back in the 90's: Sitting on a coffee table sized rock in, hmm...May/June(?) at the base of the OB couloir on Kit Carson. With a group, I was planning to go to South America with them. The self-anointed group leader gave me an uncertain vibe, he was keen to do the route the next day no matter what. As I looked up the couloir, I was mentally clicking off all the things that gave me the heebie jeebies: Aspect, slope angle, cornicing, etc etc. I began to develop a Han Solo-like uneasiness, "I got a bad feeling about this..." That night I told the leader I was out, it created a rift in the group.
The couloir slid in the morning, buried our coffee table sized rock under a few feet of dense, wet snow. Lesson: Go to a lot of
Star Wars movies, listen to The Force, esp when it says "I got a bad feeling about this..."
-Tom