I like the Leaks tool a lot. It can, however lose track of a data structure used to track a thread. There is a post here: https://devforums.apple.com/message/119423#119423
The case discussed is a 3.5KB leak originating from -[NSThread start] . I detected the same non-leak and am glad I searched online before spending too much time trying to track it.
I believe the same thing can also happen using AVAudioToolbox, detected as a 3.5KB leak originating from -[CAPThread::Start()] . I pointed out the connection (correctly I hope, but I did say “it may be”) on this thread: http://stackoverflow.com/questions/2946749/iphone-help-with-audiotoolbox-leak-stack-trace-code-included-here/3039819#3039819
So to keep this short, I hope the information will keep someone from pulling out hair thinking they have a leak when they do not.