A few months ago I had a 55 plate corsa 1200 (4cyl)with a misfire, exhaust camshaft broken between cyl 3 and 4. This hadn't had any engine work prior to failure. No cause was found and it has been Ok over the 6,000 miles since replacement.

Sometimes I just think shit happens and owners will want to try and blaim anybody.

I can't see how what you have done can have anything to do with the camshaft failure unless the belt fails.

Graham