2015 Transit Connect Transmission Whine in 3rd gear when coasting or slowing down

[Maddog]

Hi, I just bought a brand new 2015 Ford Transit Connect XLT LWB Cargo van with 2.5L engine and 6 speed automatic transmission (6F35). Before I even got it home from the dealership I heard a slight whining or kind of humming noise coming from the transmission in 3rd gear when coasting or slowing down, it is kind of like a "whoo whoo whoo" sound and is hard to hear if you are on a rough or loud road, but on a quite and smooth road it is easy to hear. 1st and 2nd gears don't make this noise and I don't believe 4th thru 6th gears do either, but would be hard to tell if they did since road and engine noise would drown out this noise. It happens at about 20 mph to about 13mph, and is loudest around 18mph, and it stops if I put it in neutral. It doesn't sound normal to me for a brand new car with 20 miles on it. Does anyone have a similar issue or know if this is just a normal sound?....or did I just buy a brand new van with a defective transmission...? Thanks.