New behavior During Feeding

[ktana]

I noticed a new behavior while my Boa was feeding on live rat and was wondering if it is normal or was the rat to large?

It is an 8 foot boa about 8 years old. The rat I gave him tonight was larger than what he normally gets. Not by much, but still larger.
First, he struck the rat while hanging off a branch. Then as he started to engulf the rat, snake would rest his head on rock then lift up and pull rat through a coil then slap the rear end of rat on rock. He did this multiple times until consumed.
Usually, he just engulfs and is done.

Sorry, if topic bothers some, not meant to. Just don't know how else to describe.

Is this normal behavior? Was the rat to big?

Thanks for your advice in advance.