Do you see this error pushing to the hub from Heroku?
/app/vendor/ruby-2.0.0/lib/ruby/2.0.0/net/http.rb:918:in `connect': SSL_connect returned=1 errno=0 state=SSLv3 read server certificate B: certificate verify failed (OpenSSL::SSL::SSLError)
This indicates that ruby is unable to find the certification authority certificates. You can probably confirm this by setting the following in your code: