iPad low memory warning, although no other apps ar

Question

I am receiving low memory warnings on the iPad (inspected via instruments) although no other apps are running, and my app has only 8 MB of live bytes.

In my understanding, iOS triggers memory warnings only, if the system is running out of resources. How can it be, that I still get them?

(To get a better understanding of the issue and the related circumstances, please check this question: Empty drawRect implementation causes memory warning)