We're flying out tomorrow morning, 6am. Both kids (1 and 3yrs) have tickets & seats. When I purchased the tickets I choose 2 window seats for the kids, since they will be in CRS. I just went to check in for the flight online and got a message saying I cannot do online check-in because they "need to assign a specific seat for the infant" ?? what does that mean? We already have seat assignments... should I call the airline or just deal with it tomorrow at check in?