Question about idle status

I’ve searched all over the web and found no answer to this. I’ve noticed something on the mobile version of AIM. If I set an alert for a user on my mobile buddies list, it not only tells me when the sign on, it also tells me when the come back from being idle.

The really interesting thing about this is that this includes buddies who have their settings set up so that you can’t see how long they’ve been idle. These are people who have the “allow users to see how long I’ve been idle” box unchecked.

I’ve tested this out using other screennames of my own. It works.

Has anyone else encountered this? I’m thinking that if my mobile list can detect this, there must be a way that my regular list can. Everything I’ve read says that it’s impossible to see the idle status of someone who has that box unchecked… but this leads me to believe otherwise.