Philipp said:
Since my edits to the original photo were really just for this course, I won't bother letting the original author of the very nice husky photo know about it. But in general, I think it's an excellent idea to let people know.
When people mark one of my flickr photos as a favorite it feels great. I imagine getting an email from someone who is actually re-using one of my photos will be even better. Maybe inspiration to try and take better photos ;-)