MSSession summaryText doubling up

I'm working on a turn based word game in the iMessages app framework. I'm ussing MSSession to compress old messages (screen shots of the game board) down to just the summaryText property. There's an odd behavior where an existing summaryText in the text message conversation is changed when a new message is added to the conversation. Here's the basic flow

-Start a new game, a game board is presented, user plays a word and submits a move

-My app is dismissed and the message is qued up to be sent

-The game board screen shot is sent along with a message "John Appleseed Played: TIN For 6 Points" just under the screen shot in the "caption" property. I've also set the summary text to the same string on this message to be seen later.

-Next user in conversation taps on the screenshot, plays a word and submits a move

-My app is dissmissed and the message is qued up to be sent. Above the qued message I can see in the converstaion history "John Appleseed Played: TIN For 6 Points".. this is just the summaryText and my app icon, the screen shot of the board no longer exists. Great!

-I hit the blue up arrow to actually submit the latest move which says "Kate Bell Played: PIN For 4 Points" but the odd thing is that the previous summaryText changes from "John Appleseed Played: TIN For 6 Points" to "Kate Bell Played: PIN For 4 Points". So now I have the Kate Bell move listed twice, one under the latest screen shot and one in the history just above it.. the John Appleseed text was simply overwritten once I hit send.

I can provide a link to a vid if this description is unclear. Any thoughts? Feels like a bug. This is all happening in the simulator.. it's possible when I get some testers it will be ok on a device. I'll update when I know.

Daniel