The message is issued by the Remote .NET Server when it receives (from the Proxy Adapter on Lightstreamer Server) a subscribe request and an unsubscribe request for the same item in sequence, in such a way that the unsubscribe request comes even before the subscribe request has been dispatched to the Remote Adapter.
Maybe, the requests were queued because of a previous subscribe-unsubscribe pair.

As you say you use a "fake subscription", do you unsubscribe the item immediately after it is subscribed?
Anyway, it is not clear how this could be related to a slow client (if we understand well, you are running your client on the ipod touch and Lightstreamer Server and the Remote Adapter on a normal host; may you please confirm?)
I assume that as long as the client is not receiving any data, the fake subscription is kept active by the client, hence no unsubscription can take place on the Remote Server.
Only a log from Lightstreamer Server, configured with the "LightstreamerLogger.subscriptions" category as DEBUG, could help us clarify things.