iPhone MKTileCache error - map

In console I get the following error:

[MKTileCache synchronize](MKTileCache*, objc_selector*) called while in background!

Scenario: from a view controller I load the map activity, go back and exit the app using home button.

Does anyone know how to get rid of this error, I think that might be a memory leak.开发者_C百科

Thanks in advance.