Help with Sudden Font Change

The body and title fonts of my blog seem to have changed overnight! I can’t seem to figure out what I did to cause this. The text of the body and title posts have changed to a bold font I can’t recognize – I checked the Google Font plugin I use and the css style sheets, and I still can’t figure out what’s going on. It appears on all browsers (I’ve tested it on three so far). I’ve checked that I don’t have any bold or strong tags open – at first I thought it was my original font just being bolded, but I don’t think so.
This is my my site from a month ago.
And this is what it looks like now
Any thoughts on how to troubleshoot this would be greatly appreciated.
Thanks!

The page I need help with: [log in to see the link]