I am not really sure how we got upgraded. We did book a bit in advance. I have gone on Carnival 5 times and have never received this type of upgrade this quick - you know, without them running a past guest special. You don't hear me complaining.
Sorry veterancruiser39 - Didn't mean to spike some ill feelings you might have for Princess. I definitely would be angry if I was offered an onboard credit and they have them take it away.