Apologies for late reply.
It can happen in the case where client connection from AppWarp server breaks due to any kind of interupt at client side. For example: Intermittent network, Incoming calls etc. In this case when connection breaks, the server deletes the user session.
To handle this scenario, you can use Connection-Resiliency feature. If you use this feature, then the server will keep the user's session in case of any interupt for specified time-period. Once the interupt is over then the connection can be recovered by calling recoverConnection API. Please go through the above tutorial for more details.
Let me know if you have any further queries.