Auto gearbox doing odd things

[treeman]

I’ve got a 2003 E53 3.0d auto and had it for 14 years. Over the last year the gearbox has begun acting strange. Initially it would do odd Rev up and drop for a fraction of a second when going up hills but ran smooth apart from that. Now it seems to not change up quick enough. I’ve started flicking onto manual change up as it is revving too much before changing up, almost like its in sport mode.
I’ve asked the dealer and he says they’ll reset the gearbox “driver memory” to see if that cures it. Has anyone had this done? Might it help?
I’ve noticed the fuel consumption has dropped from 30.0 to 27.7 as well so something’s not right.
The gearbox has done 120k miles on original oil.
Any advice welcome.