I don't mean to be a pain but I just wanted to make sure you posted the right URL. I just read an article on authoritydomain that came a few days ago. It says that several Url shorteners are using 302 redirects. Twurl.nl, hex.io, eweri, and fon.gs are all "dirty 301 redirects"
The article goes on to say that tinyurl, bit.ly, ff.im, and is.gd are all good examples of a clean 301 redirect.