Add watcher does not inform

When adding a watcher to a bug the person that has been added isn't informed that she/he has been added and cannot verify who did add her/him to the bugreport. (bad - could be used to spam)

This information is also not added to the log of activities of the person that did add the other person. (not that bad)

I doubt this information isn't stored anywhere. It would be nice if at least the person that has been added by another one would get this information (Something like "You've been set on the Watcher's list of Bug #1234 by xyz.") either inside the activity log or by mail.