Disabled User, Mobile-Device (Active Sync) still has Access 24h after disabling Account

Hello, 

i encountered following issue:

I disabled an User in AD, but the mobile devices of the corresponding User still had access even 24h after disabling the account (iphone 5s, Blackberry Q10). My predecessor was known to abuse some access rights (suspicious gpos, phantom users with way to many rights, private folder access...).

Our System: Windows 2008 R2 + Exchange 2010 SP3

Are there any hidden settings (in Exchange powershell, ADSI-Settings etc...) to extend the access-validity of mobile devices?
Or is this a normal behaviour?

Thank you and best regards, 

Georg