imessage not indicating delivered
my imessages are not indicating that they are delivered. The person I'm sending them to is receiving them, but there is no delivered stamp at the bottom. Then a couple of minutes later all the messages turn green as if I sent a regular text. I'm using 9.0.2. This problem only seems to be happening when being sent to a select few contacts. I believe that the recipient hasn't updated yet. Could this be a cause for the problem? Is anyone else having the same problem? This only started last night. Before everything was working fine with all contacts.
iPhone 5s, iOS 9.0.2