Scroll up. Chances are very, very good there was a prior roll that was below 0.9, accompanied by a message that said "Your Gemcrafter's Chisel will break soon."
As stated in a recent update note, CNR sources will produce at least one bit of appropriate CNR before the tool will break. So what that means is that if a roll is made that might break the tool, it's remembered until a bit of CNR comes out.
Anyway, check back through your log, and you should see what I mean.
