Are Physics a bit messed up in 4.6.1?

I'm noticing some weird behaviors in 4.6.1.

A cluster of rigidbodies that settle, after a few seconds, suddenly re-explode and displace each other, and also on the ground plane, repeatedly until various pieces are flying off at rapid speeds off into the distance.

Bug?

 

Interesting, I also recently discovered weird behavior of the same type (in 4.3.4f1) when I add a continuous force and torque to a rigidbody that is simultaneously colliding with another rigidbody. I am hoping it will be gone in physX 3.3.