I have had the opposite happen, shooting with multi pattern metering. First time I was shooting outdoors, sunshine, and some of my shots of my grandson were severely over exposed by 3 stops, prior to this I had been shooting indoors at f2.8. Second time again outside, sunshine and the same thing happened, I even tried spot metering. Not sure if its a lens issue? If it happens again I suspect I will have to send it off for repair.
Geoff