iOS instruments' ObjectAlloc, GeneralBlock-0 net count

[counciler]

I have this simple app running on my phone, and after playing it for a while it crashes. I've been pretty diligent about trying to not leak memory in my program, but everyone makes mistakes, so I boot up instruments and go to the ObjectAlloc/leaks screen. The leaks stays empty and obviously the ObjectAlloc fills up. The ObjectAlloc graph stays pretty steady. Even all but one of the numbers stays steady. The GeneralBlock-0 #net is constantly going up and never goes down (#net = #overall). It goes up even when my program is mostly idle, except for an NSTimer running. I looked at the objects being created and they're all QuartzCore objects. So far all I have is a bunch of UIImageViews and I'm not dealing with Quartz directly. So is this normal? Could this be causing my app to crash when testing it on the phone? The bytes always stay at 0 so I assume this means it's not taking up any memory. But it's curious why it would do this.