Here's the most curious thing that happened:
One of the testers for the first version of our Smart Home Skill had his Alexa setup made for testing. He has decided to use it also at home. After that, we've finished the certification process. He thought he was using the live version of our Skill, and he kept using it every day. It was already long time ago, 90 days should have passed at least 3 times.
Some time ago we've decided to update our Skill, created a development version and started beta testing it. Then 90 days passed, and every tester wasn't able to test any more. Except the Ghost Tester, who's activity we could still see on our development Lambda.
In this case nothing bad happened, but it really might have: like information leak. I hope You'll address this issue.