Full Metal Wheelbarrow

I was making decent progress with the left front of my cardi last night and then I realised I'd somehow managed to drop a stitch right at the beginning of a row about ten rows previously. How do I do these stupid things and not notice them?

At least this time I was able to unpick back to it and recover without unravelling the whole thing and I've already passed the point that I had to start unpicking from. I just wish I wasn't quite so dozy.