It's not. Atleast not possible hours later like in the OP'S case.
Her snake wasn't dead. Just in extreme respiratory distress, cold and listless from being so ill.
I once worked in a petstore and a family returned a "dead" corn snake. It was sealed in a zip lock bag and put into a refridgerator. I was doing inventory and had to count the dead. So I had them out on the counter in the back and got called away. Took me a while to get back and wouldn't ya know it the little corn snake was moving. Low metabolism + really sick animal = pseudo zombie snakes.






