Cat suddenly being mean :/?

Ok so a little over a year ago I got two female kittens both from the same litter. They play all the time and have never been apart, both are indoor cats. Two days ago i took one cat (we will call her Elle) into the vet to get spayed. I took her into the vet she was great, a little trooper. She is a very shy cat kind of mopes around a lot, but she did great. When i came home without Elle my other cat (we will call her Sue) searched for hours and hours trying to find her. Well I was able to pick Elle up from the vet the next morning. I brought her home let her out of her carrier and she ran straight for the food. The carrier was in another room and Sue didn't see Elle at first. The first thing Sue did was run into the carrier and sniffed it for a few min. Then she came out and went to the dining room(where we keep the cat food/water. Sue saw Elle and started hissing and growling at her. Elle doesn't seem to be phased by it she doesnt growl or hiss back she just looks at Sue. But this has been going on for about 2 days now and Sue will not stop growling... Will she ever get over this and be nice again??