Thank you Dario for responding.

The session was still valid on client side and was waiting for new messages which server will never push to anymore.

One more thing. If client is in polling mode, and the message pushed between two polling request, will the message still be pushed to client? Even for some reason some polling request not reached server? Like this (29-33 missing)
09:30:00 10.35.56.153 10.35.56.153 Polling (28) to session: S384410adb026c838T2016441
09:30:48 10.35.56.153 10.35.56.153 Polling (34) to session: S384410adb026c838T2016441

Thanks