I have te same with 09 4.8 auto, just had all the checks doe and found out apparently there is a design fault with that type of auto box where it tries to "grab" 1st gear when slowing down.
Nissan aust / international are aware but won't do anything as it does't cause any damage to anything.
1 of the other members mentioned to put a bit of nulon in to help the hears "slide" smoother, haven't done it yet but will do