I wonder if this is because it is cached creds. Did you try to:

1. Open cmd prompt

2. type "klist.exe purge"

3. Establish a new connection

Additionally, you can install the Kerberos Configuration Tool: http://www.microsoft.com/en-us/download/details.aspx?id=39046. This will identify any issues with your SPNs and allow you to correct them.

A server reboot would also flush the credential cache. Hope this helps!

~Slevin