It is normal for them to be defensive after eating. I usually make sure to leave well alone after they eat. Having to pick them up and put them back in their tank is needless stress and there is no reason to feed them outside of their enclosure. I usually just remove a few obstacles and let them eat right in front of their hide.

I've had a couple of my snakes that are usually very calm actually strike at me just from changing their water bowl after they have eaten. They can't move fast to escape with a rodent in their belly so they have to act scary if they feel threatened.