SEP 12.1 RU4 SEPM just downloaded the RU6 (6168.6000) client package

My SEPM running RU4 (12.1.4013.4013) just automatically downloaded the client package version for RU6 (12.1.6168.6000) yesterday. That makes it available for distribution to clients for upgrade.

I'm thinking it is not a good idea to put the RU6 client onto machine reporting to an RU4 SEPM. Am I right, or is there something special in this release where that would actually be recommended to do?

Why did it automatically get downloaded & made available if the SEPM has not been updated yet?

Thanks