Where are GLKShaderBlockNode leaks coming from?

Question

After running the Leaks Instruments on an app that I am developing, I see a lot of leaks relating to GLKShaderBlockNode. Some are GLKShaderBlockNode, some are Malloc < varying sizes >, and some and __NSCFString.

I've searched for this online and at Apple's dev resources, but could find nothing about GLKShaderBlockNode.

Responsible Library : GLKit

Responsible Frame : -[GLKShaderBlockNode copyWithZone:]