Email from Valve

Hi.
Yesterday, we reset your Medic achievements because we mistakenly believed you had hacked around the system to get them. Today we discovered a bug in our code that resulted in you being incorrectly flagged as cheating. As a result, I'm emailing you to apologize for our error, and to let you know that we've decided to award you the full set of Medic achievements.
Have fun with the Ubersaw, Robin Walker.

How awesome is that! Today I briefly logged in to TF2 with Blue Blood and found out that most of my achievements had reset. Turns out quite a few people's had, so I didn't think much of it!

Time to try out that ubersaw me thinks ;)