Okay, I only just noticed this today after editing a post of mine a couple of times, but it seems that every time you submit a post it adds a space after every single Fullstop in your post.
This means that any time you end up editing a post you add an extra space. To every fullstop. In addition to any adjustments you actually intend to make.
The Change seems to be made during submission and occurs in all '3' of the posting/editing methods I've found. (Initial posting, in-line edit and full edit. )
Not world ending, definitely annoying.