Well, today my mother and I ran out with our cats to an ASPCA truck to get spayed. I opened one of the kennels to put in some food, and the cat runs out.
She ends up in the underside of an SUV, and I had to climb under the car to get some visual. My mother calls my twin sister and asks to come down. (My sister is the cat's owner)
After we pop the trunk, we got her out. But my twin is still acting as if she were stuck in a place where we could never get to her. She didn't even ask me if I was ok.
Am I being selfish, guys?

I dont get it. How could you be selfish for getting the cat out?
She was in shock when we got her out. But she was fine almost immediately, and my sister was treating me like shit and not appreciating what I did.

Ohh. No, then id say SHE was being selfish. You got her out, she was in shock, that happens its not like the cat died, right? it would have been selfish to leave her in there. tell your sister to grow up and look after her own cats in future, then =/
Thanks. That makes me feel a lot better. :)

Good. You shouldnt feel bad, you did a good thing ^_^ ❤️
Actually your question should have been more along the lines of, "Is it wrong for me to think that she was crossing the line about worrying about her cat more than me".
Sorry about that quick detour, for some reason I am in correct mode at the moment (and of course that means a zillion people are going to correct me soon, but hey it's all relative).
Your sister is entitled to worry about her cat (after all since she did not even ask if you were okay, my guess is that she treats her cat as if it were her child) but she should have at least asked if you were okay or should have thanked you.