Ex Pass Hack/Trick?

Its a small sample size but considering the current distribution it could very well be the answer.

2 of my level 40 locals and a level 30 (one of the level 40's alternate) decided to try this method. They stopped playing for 2 weeks. No catching, spinning, raiding, nothing. Only opened the app to check if they got an invite from prior raids. This weekend they decided to reopen the app and do a raid. We did a raid together on saturday and today all 3 accounts received an ex pass scheduled for 1/16 for that same raid we did and everyone else we knew that was present at the time of the raid (myself included) who have been somewhat active the past 2 weeks did not get it.

I think its worth a try since there's not much incentive for me to play atm. So i'll be revisiting this. If anyone else wants to give this a try let us know your results.