Change after Spay

Yesterday Ella got spayed, everything went well. Poor baby doesn't want to eat her hard food. Good thing we have wet food too  But now that i think of it i did notice a change. Her tail is ALWAYS pointed up. I've only realized this because I used to have another cat (Nakine) and after her spay her tail ALWAYS stayed up with the tip of her tail curled. My question is Why? 

Does anyone know why?

Thanks.

Al lI know is a tail up in the air is usually a sign of a happy cat .  ( I'm surprised that right after a spay she's happy )

This thread shows a chart of cat tail positions and what they mean:  http://www.thecatsite.com/t/211771/cats-tail

 that was funny. well i guess i have no more worries or confusion!..lol