Judder when engaging drive?

Stationary in neutral, put into drive. Release the brakes and there's a distinct judder for a few seconds.
Fortunately it's under warranty and due a service in a couple of thousand miles, but I'm thinking maybe the auto trans fluid needs replacing? Or maybe something more serious? FWIW it's got 73k miles on the clock.
TBH it's more of a tranny thing than a spark/fuelling thing. I don't know how to describe it, but it's not an engine hesitation, more of a judder when taking up drive. If it was a manual I'd think the clutch was glazing up and I'd give ir a couple of 7000rpm standing starts (used to work wonders on my old Subaru Impreza Turbo), but as it's an auto that's not really an option


