2.5 Dashboard layout suddenly looks like stylesheet is broken

I upgraded to 2.5 last night and everything went smoothly. Configured it all, had everything working fine, it was great.

Logged in today to make a post and discovered that my dashboard design had changed somehow, overnight, as if the stylesheet didn’t load properly.

Here’s a screenshot:

https://joshuameadows.com/images/2008/0422dashboard.jpg

It all works fine still but it looks strange, across several browsers, and I didn’t know if this was a precursor to a different problem.

I hadn’t done anything whatsoever to my site between this morning and last night when it was fine.