Stars and PMs - Possible minor bug?

It's a really unimportant issue, but I noticed something weird yesterday: it seems that, when you have given a certain user a star for a private message in the past, you can't do it again even when it's a different PM. When I click the button, the star count of that user doesn't increase (I still get the "You must wait a few hours" error message if I try again right after that, though). Is this a bug, or it's just the way it's intended to work?

This is the way its intended to work. PM's are quite private, so we aren't monitoring the content of the private message. In order to combat people abusing private messages (even if it are different messages) we count giving a private message a star an act as a whole, you may do it once to a specific user. Any more will act the same as if you were giving the same post a star. The difference is that we can monitor posts, so we can see to what you have given a star and rule out any possible cheating.

Makes sense. Thanks for the clarification!