Equally wide tree rings can show different colour gradients, as earlywood and latewood widths vary. These variations are caused by weather conditions, and sometimes, in larches in particular, by the larch budmoth.
The width of a tree ring is determined by many current and previous year factors. Weather conditions play a key role in this. Relevant to this example is not the narrower latewood of 1325 compared to the previous year, but rather the wider earlywood.
The higher proportion of earlywood in the ring could indicate the early start of growth due to mild temperatures in spring.