I was behind a cyclist on the way home last night who, several times, put a hand behind her back at waist level and wiggled her fingers for a few seconds, as if shaking off a bit of oose. It was done on both sides I think.
I'm guessing this was a signal of some sort directed at me, and my first thought was, to my shame, that she felt I was too close. I don't think I was, but did pull back a little as too close is quite subjective.
Is this a recognised group signal?