Someone else is signing my name

In the dream I'm watching my own hand move the brush across the paper, and the characters are good — better than mine, actually — but nothing I wrote in my life would look like that. I try to pull the hand away but it keeps going, finishing a piece I've never seen. When I wake up I check my own signature on yesterday's envelope and it feels like a stranger's, like my calligraphy is just something I rent.