IPad low memory warning, although no other applications are running, and my application only allocates 8 MB

Question

I get warnings about low memory on the iPad (checked with tools), although no other applications work, and my application contains only 8 MB of live bytes.

In my understanding, iOS only triggers memory alerts if resources run out on the system. How can it be that I still get them?

(To better understand the problem and related circumstances, check this question: An empty drawRect implementation raises a memory warning )