While mapping today I've noticed something very unusual: every object I've edited before this Wednesday is slightly larger than every edit I have made since. After doing some digging in the XML data, the change seems to have occurred at some point on the 6th of November between 11am and 4pm GMT. After doing some physical measurements I've discovered the dimensions of every line and every area on the OGF map has physically increased in size by between 6.25% and 8%. The size of objects relative to the scale on the bottom left has stayed the same.
How was I able to find such a small change? I scale my edits by using a transparent plastic ruler - this provides an objective and literal yardstick to which I measure all my mapping against. To put this in physical terms, a row of houses I have mapped should be 8cm wide, but now they are about 8.5cm wide on the map.
Why is this important? Ordinarily a change of 6.25% might not seem like much, but if I mapped a row of 16 houses using my existing measurements it results in a house-sized gap at the end of the road. If I started mapping in detail from the opposite sides of the same street, the buildings would be misaligned in the middle.
Does anyone have any idea if this is an OGF-wide change, or is this something my computer has done itself? If it is the latter, is there any way to revert this change?