TPA3118D2: The safe distance requirement between the output inductors ?

Part Number: TPA3118D2

Tool/software:

Hi 

My dustomer are asking the safe distance requirement between the output inductors, can you help suggest?

Now customer's layout the inductors distance is 1.4mm, do you see any issue. 

Also is there any requirement for the inductor's  Coupling coefficient if the inductor are put so close ?

Customer's schematics and layout as below