Strange "new post" email sent from "root" on youtube

Two of my blog’s subscribers (maybe more, I’m not sure) got an email from Spoon, my website, even though I never sent an email. The address it was sent from was donotreply@wordpress.com and contained a message that said “New Post on Spoon” with a link to youtube. We have never posted anything on youtube, and did not send an email to anyone. I’m not sure if it’s a hack or not, but it’s concerning. Any ideas??