Facebook on phone

Hey,
So today I used someone elses phone (iphone) to login on fb, I'm pretty sure I logged out afterwards. I'm curious if that person could still login on my account and do I have to change my pw or am I fine?
Used safari app.

 

You're probably fine, and no they can't backspace and somehow be able to use your account.

For safety purposes though I'd go ahead and change my password. I usually do this after logging in a computer that isn't mine, you never know which ones have keyloggers in them.