Is there a reason my puppy would choose to pee in her open crate?

She’s 4 months old. Shes crate trained but we don’t let her go more than a few hours in it at a time (overnights she goes a few hours, and then during the day she’ll get crated once or twice for an hour or so). She knows to go out to potty. Never had an accident in her crate ever and it’s been two months. She does sometimes have pee accidents inside the house but that’s to be expected, and even then it’s only maybe once a week now. She’s let outside every 30 minutes max, then on top of that anytime she whines, looks at the door to go out, etc. She never has poop accidents in the house.

Tonight she didn’t even give a warning she needed to go out. I had let her out 20 minutes before and she peed. She was chilling then went into her open crate and peed? I almost feel like it was her attempting to mark vs actually had to go but is that common?

Idk any advice or information helpful. I said no in a stern voice since I caught her in the act, took her outside, but she didn’t pee outside. Just confused is all and curious if that’s a normal thing for puppies to do. And if there’s any advice on how to handle it if she does it again.