A little pedantic, but once I noticed it I couldn't unsee it.
When I hover over the tag score for a user who has asked and answered a question in the tag on Meta, there is no space after the first period.
For example, if I hover over my score for the discussion tag, I get this:
I also tried an example on the main site, hovering over Jon Skeet's tag score for generics. Sure enough, the space was there. (I haven't asked a question on the main site, so couldn't use my own profile.)
UPDATE: As pointed out by @MichaelLiu on this question, the space is now missing on the main site too. Here's his image:
Can we add the spaces back?