How can you find out if someone is offline on Facebook just for you?

[Ana]

I noticed something odd and wanted to see if I can get to the bottom of it. There is this friend on Facebook who used to always appear first or second on my chat box on Facebook (the one above more friends). Even when that person would be offline, they would still appear second or third in the chat box. Everytime I would post something, and that person appeared online and second in my list, they would immediately move up to first in the list.

However, I noticed a couple of days ago that that person not only doesn't appear in my chat list first or second, they don't appear at all. Ever.

Does this mean that person has chosen to be be offline on Facebook just for me?

Thanks