Gearbox juddering when I pull away, is this the beginning of the end?

My car's been doing something odd for the past couple of weeks. When I pull away from a standstill there's a slight judder, like the car hesitates before it engages. It's subtle, and only happens from a stop, but it's definitely new. The car's a 2017 model with an automatic gearbox and about 120k on it. Naturally I've been googling and terrifying myself. I read an Expert guide to automatic gearbox problems to try and understand what I'm dealing with, and juddering on pull away seems to be a recognised symptom of a few different things, some minor, some not. Has anyone had this and it turned out to be something simple? Or is this usually the start of an expensive road?