We have encountered memory leak as well.
Steps to reproduce: (Warning: Do not install the power tools if you don't want to end up resetting your phone version to be able to test your game)
Install Visual studio developer power tools support to the device and after that every scene change will just grow the memory usage, never release it. We have done the same two times with the same result. After we reset the phone back to normal version without power tools support, memory starts to behave much better. This might be reason why examples behave differently and also it seems that problem is not coming from Construct2. When power tools are installed to the phone, we cannot test our game, because eventually it always ends up eating all the memory quite soon after the start of the game.
Good thing is that with visual studio performance and diagnostic tool it does not need power tools to be installed to see how memory behaves in the phone. This is something we just noticed and have not yet contacted Microsoft about it. When we have little more time, we will do that, but if someone has spare time and good contacts, it would be nice to introduce the problem to Microsoft as well.