When navigating from one layout to another, and returning to the previous layout, with fade transitions, the events "every xxx milliseconds" take some time to trigger.
You can check my forum post for a more detailed description: http://www.scirra.com/forum/viewtopic.php?f=3&t=8848&p=67862#p67862
I can't provide my cap right now, but it should be easy to recreate a similar situation.