Pinterest Etiquette

I do love pinterest -- it's a great place for inspiration and for organizing ideas for future projects.

I first became aware of it several months ago when someone "pinned" a photo of one of my projects and the link showed up in my stats.   Now I love it when someone pins something -- it's an extra pat on the back for something that I've usually worked hard on.  And I usually click through to check if they made a comment or if someone else repinned it just 'cus it's a nice ego boost.

Tonight though I noticed that someone had pinned a photo of something I had made and added a link underneath advertising a workshop to make that same pattern.  I don't know what the etiquette is for this type of situation but it bothered me enough to send them an email asking them to remove the link.  

I get using other people's images for inspiration and I think that's awesome but is this situation crossing the line?  What do you think?

edited: I received a reply almost immediately and the pinner agreed that adding the link underneath was crossing the line.  I hate confrontation but I'm glad I said something.  I still would like other opinions though . . . I get that I'm putting things out there for the public but where is the line?