Accidental re-lactation

This is the weirdest thing. About three to four weeks ago I started watching a friend's four month old baby, one day a week for five hours. Last week I noticed my breasts felt kind of achy. I thought, oh, it's my period. Sensitive breasts aren't usually my problem, but it does happen every once in a while. I kept feeling hungry, even after a big meal. I watched the little boy on Friday. Friday night I went into my daughter's room to lay down with her and rub her back until she fell asleep, and I had a let down!!! I couldn't believe it. I haven't nursed her since April of this year. I couldn't hand express at all for the last several months that she was nursing. Sure enough, after she fell asleep I got up and went and tried to hand express and there was colostrum. I looked around online and couldn't find any non-nipple-stimulation instances of re-lactation. Hopefully the little let down feelings I'm having and the fullness will go away after a while. What amazing things our bodies are.