Hey David,
I believe you are speaking of the font at the top of the posts inside the gray box? Universally the font size wasn’t changed of the main site but there has been alteration there.
Is the portion of text that is smaller on this image and what part specifically?

I believe the font of parts A B and C have been reduced in size as we did change the look in that portion of the site yesterday. The font size of D I don’t believe has changed.
The fonts do look different in other browsers – this screen shot is what I see in Firefox on windows but I’m sure you have a different perspective. What portion specifically is causing problems for you?
Abraham