Hi, just wondering if anyone can shed some light on an upgrade my girlfriend got flying HKG-SYD on 9JAN14. Here are details.......

-Ticket was issued by CX and paid for Y.
-Has no status with CX (not even signed up to the program and first time on CX)
-Checked in online the day before flight
-Went to the electronic boarding pass printer but would not accept ticket.
-Lined up, check in agent took an age, tapping away on the computer (saying nothing) Gives her the boarding pass without saying anything of the upgrade to Y+
-My girlfriend didn't even notice the upgrade until 10mins later due to not even being told anything at check in.

We are just curious as to why the upgrade was given. She arrived at the airport very early and would of been one of the first to check in. Also, she had pre-selected a special meal (if this makes any difference) and there was no equipment change. Plane was very full.

So was she just extremely lucky or is there something else in the CX upgrade world that determines who gets the upgrade? Cheers