Oh man, I've done that more times than I care to admit!! And when it happens I always feel SO stupid that I've done it again but it's just one of those things I can't seem to remember. Thankfully my machine is (so far) unharmed by my lack of attention.
One time I even heard a "click" as a bit of needle shrapnel hit my eyeglasses. Never thought I'd be grateful that I have to wear glasses but now I am!