iPhone automatic update on setup? Warranty length?

Hi, I just bought a new iPhone 13 and have a concern regarding two things.

1) After initial setup, it shows the iOS is 16.1.1 (not the newest verion currently available). I understand iPhones 13 were by default set to iOS 15. Did the update to 16.1.1 take place automatically during the setup or does it indicate that the phone had been used before?

2) The phone was bought and first used on 13 Feb, but it says the warranty will expire on 12 Feb next year. Shouldn't it expire on 13 Feb next year? Again, can this indicate that the phone has already been used before?

Thanks for clarifying this...