I recently ran into an issue with memcache, only to find out, looking at yii2 issues, that there is a known problem, that yii2 handles by setting differently time in seconds less than 30 days and differently (adding epoch) if time in seconds is more than 30 days.
Unfortunately, this finding hasn’t been applied to Yii 1.x i know that Yii 1.x it is no longer supported and only language version related issues are reviewed, but i d really like to see it being introduced in a future release.