Well we just got the same email from Celebrity. We are in a concierge mid ship cabin and they are offering for us to "bid" on an upgrade. The offers are for all the different suites ranging from 500 to 1000 pp and 3000pp for the week but you don't choose a specific suite, you get what they give you. They said aqua class "from" 50pp so I clicked to see what it said and the minimum bid I could do was 500 so I did not go any further.
Mine also said only a few were offered this chance to upgrade. We got what we could afford and some perks so we will be happy with that.
This was also a Bermuda cruise.
Interesting that they are trying something different we will see if there are any last minute takers, it will not be us.