Google api でinvalid_grantが発生したときの問題

Message from application: Authorization failed.  Server message:
{
"error" : "invalid_grant"
} (Signet::AuthorizationError)
/rails/app/path/vendor/bundle/ruby/2.1.0/gems/signet-0.6.1/lib/signet/oauth_2/client.rb:966:in `fetch_access_token'
/rails/app/path/vendor/bundle/ruby/2.1.0/gems/signet-0.6.1/lib/signet/oauth_2/client.rb:983:in `fetch_access_token!'
/rails/app/path/vendor/bundle/ruby/2.1.0/gems/google-api-client-0.8.6/lib/google/api_client/auth/jwt_asserter.rb:105:in `authorize'

サーバの時間がずれていたので、ntpdateで時間を合わせた

/usr/sbin/ntpdate ntp1.jst.mfeed.ad.jp