Renamed user in Active Directory/Exchange not correctly displaying in Outlook calender

Renamed user in Active Directory/Exchange not correctly displaying in
Outlook calender

We renamed a user via the SBS2011 console. It appeared to update
everywhere. However when other domain users use Outlook to connect to the
user's shared calendar it still has the old username.
Ex: rename User1 to User2. When User3 connects to User2's shared calendar
it still shows User1's name in the calendars list.
Active directory has the correct info, and everything seems to be in
place, our only issue is with the wrong name showing up in the shared
Outlook calenders. Removing and recreating the account isn't really an
option because of all the information tied to this specific user's
account.
Why would this be happening?