i noticed that and this is specifically to iPhone users. It seems that when I am chatting with my friends (who are on iPhones), half way through, the message starts to be lost somewhere in the server, I see the acknowledgment sent to server but I don't see the acknowledgement sent to the users. I am pretty confident that they did not close the app because we are in the middle of a conversation and it happened to me on both friends using iPhone. I have another friend using Symbian phone and it doesn't seem to display this issue.

Anyone experiencing this?