Agreed, milk does slow the absortion rate down and is better before bed.
After a workout your body will absorb nutrients quickly and is better to use water as not to slow this down with milk.
A good michelar cassein (I think thats how its spelt) in your protein before bed should release for about 4-8 hours. They advertise sometimes that the release is more, but I believe this is up for debate, anyhow, a slow release before bed is alot better than getting up in the middle of the night and preparing a meal.
I mix this with milk, the only one for the day.