Trying to remove old Exchange 2010 - Warning 3005 - MSExchange Front End HTTP Proxy

I have upgrade to Exchange 2013, moved all the mailboxes and everything seems to be working fine.  The final step is to remove the legacy Exchange 2010 server and UM server. 

The TechNet guides explain that I just need to uninstall Exchange 2010 on the old server.  So, I thought that I would first try shutting down the old Exchange 2010 server and let the new Exchange 2013 ride solo.  All seemed OK, I was getting emails in Outlook 2010 and on our smartphones. But, the next morning after re-launching Outlook 2010, even though it said it was connected, I was not receiving any new email.

I turned back on the old Exchange 2010 server, and then all of the emails starting coming into Outlook 2010. 

Looking at the event logs on Exchange 2013, I see that I was getting 3005 warnings regarding [Autodiscover] Marking ClientAccess 2010 server srv2010.domain.com (https://srv2010.domain.com/Autodiscover) as unhealthy due to exception: System.Net.WebException: The operation has timed out....

Before I uninstall Exchange 2010, is there another way to remove this apparent dependency on the old server?

Thanks.. Chris