How far is the airport from the last night hotel? If it is an hour or more I am thinking that might be the reason. I would call
ABD and ask.
I have a similar issue but it is on my inbound flight to Italy in May, the website states flight to land no later than 3 pm, so as soon as I received confirmation from my
travel agent that I got the trip I booked my air as I wanted to use miles. The flight lands in rome at like 145 or so then I received the ABD paperwork and it said no later than 1 pm. Oh well I am not worried about it.