It's a little IC logic for the experience you gained. We like to provide those because it links the reward (the XP) to what you did to earn it. In this case, saving the life of a groupmate who seemed to be quite intent on getting themselves killed.
As a counterexample, if you got XP (and no other info) for an especially spiffy role or description, it would probably seem to you that it came out of thin air. You might have been on for an hour already, and you're off buying pies or killing kobolds, but that's when the staff member started checking. So we encourage people to send a little IC rationale along with the XP, so you say to yourself "Oh. It's for the extra-cool desc. I'll try to stick one of those on all my characters!"
