2 month old puppy sometimes ignores puppy pads — advice?

Hi everyone,
my girlfriend and I got a German Shorthaired Pointer puppy on December 20th. He turned 2 months old on December 31st. Despite some nighttime crying (he sleeps in a crate in our bedroom), mostly because he needs to go potty and occasionally because he wants to play at very inconvenient hours, he’s actually doing really well — especially considering he was separated from his mother quite early.

He adapted very quickly to using puppy pads for peeing, and for pooping he usually goes to the door to let us know he needs to go outside. He’s very smart.

However, in the last couple of days, despite all this, he has peed on the living room rug twice in a row. If we’re not immediately ready with shoes and jacket and don’t catch the exact moment he needs to go out, he just goes wherever is easiest for him.

How can we prevent this? He seems to understand that he should pee on the puppy pad, but sometimes he just does whatever he wants.

Thanks in advance!