two CAS servers and changing two autodiscover URLs

I have two exchange 2010 cas servers in two remote locations.  CASa serves for location a's (LOCA) database and CASb serves for location b's (LOCB) database.  LOCA has url mail.loca.domain.com  and LOCB has mail.locb.domain.com.  we recently updated LOCB to have mail.siteb.domain.com by configuring:

Set-ClientAccessServer -Identity server –AutoDiscoverServiceInternalUri https://mail.siteb.domain.com/Autodiscover/Autodiscover.xml

Set-OWAVirtualDirectory –Identity "server\OWA (default web site)" -ExternalURL https://mail.siteb.domain.com/OWA
Set-OWAVirtualDirectory –Identity "server\OWA (default web site)" -InternalURL https://mail.siteb.domain.com/OWA

Set-OABVirtualDirectory –Identity "server\OAB (default web site)" -ExternalURL https://mail.siteb.domain.com/OAB
Set-OABVirtualDirectory –Identity "server\OAB (default web site)" -InternalURL https://mail.siteb.domain.com/OAB
 
Set-WebServicesVirtualDirectory –Identity "server\EWS (default web site)" -ExternalURL https://mail.siteb.domain.com/ews/exchange.asmx
Set-WebServicesVirtualDirectory –Identity "server\EWS (default web site)" -InternalURL https://mail.siteb.domain.com/ews/exchange.asmx

Set-ActiveSyncVirtualDirectory –Identity "server\Microsoft-Server-ActiveSync (default web site)" -ExternalURL https://mail.siteb.domain.com/Microsoft-Server-ActiveSync
Set-ActiveSyncVirtualDirectory –Identity "server\Microsoft-Server-ActiveSync (default web site)" -InternalURL https://mail.siteb.domain.com/Microsoft-Server-ActiveSync

Set-ECPVirtualDirectory –Identity "server\ECP (default web site)" -ExternalURL https://mail.siteb.domain.com/ECP
Set-ECPVirtualDirectory –Identity "server\ECP (default web site)" -InternalURL https://mail.siteb.domain.com/ECP

Set-OutlookAnywhere -Identity "server\RPC (default web site)" -ExternalHostName mail.siteb.domain.com

Set-ClientAccessArray -Name "SITEB" -Fqdn "mail.siteb.domain.com"

Get-MailboxDatabase | where {$_.ExchangeLegacyDN -eq '/o=Domain/ou=Exchange Administrative Group /cn=Configuration/cn=Servers/cn=mail.loca.domain.com/cn=Microsoft Private MDB'} | Set-MailboxDatabase -RpcClientAccessServer 'mail.siteb.domain.com'

All was well with the certificate swap; however, when I changed LOCA to use the url mail.sitea.domain.com and swapped the certificate, siteb got a certificate warning about mail.loca.domain.com (sitea's old certificate).  All urls and links are set correctly.  Why is siteb getting this warning on all outlook clients?