My sister's last name?

It seems like my sister suddenly has a different last name than before.

(I'm going to use the last names of Smith and Torganschuwanaway instead of our real last names to protect our identities. )

I could have sworn that my sister had the same last name as me (Smith), but ever since she got married, her last name is coincidentally the same last name as the person she married (Torganschuwanaway). I just find it very bizarre that someone I have known my whole life suddenly has a different last name. Does anyone else remember my sister having the last name of Smith, or is it just me?