Go here:
http://casascius.uberbills.com/?type=1&status=active (warning, will take a long time to load, may crash browser)
Hit CTRL+F and type in your firstbits. If it doesn't say it's Active or you can't find it, it's possible it was compromised.
When I said the API was down I mean this:
https://blockchain.info/q/resolvefirstbits/1Q
Replace the "1Q" part of the above with your first bits and see if the page loads. If it's not loading, there's something wrong with the API, typically.