When I move a face/edge, more than just that face/edge moves

Just noticed that when I move an edge while in edit mode, on a simple box-like object, most of the whole object moves. Now I’ve just made a cube and tried to pull out a face and the whole object moved.
(using 2.8)

You probably have proportional editing activated. That is the little round icon next to magnet icon in the top bar.

Hmm, it’s stopped doing it now, and I can’t reproduce it again. Weird. But if it does it again I’ll check that out. Thanks.