Pooping in diaper at night

Katelobster

my 24-month-old has been trained for a couple months. She will pee and poop in her potty while we're in the house without any prompting. It's normal for her to poop 2-3 times a day, so she's still pooping in the potty during the day and does not seem to have fear or reluctance to do so. But she's also occasionally pooping in her diaper early in the morning for the first time in her life. Is this something I should be concerned about? Is she likely intentionally holding it or has PT just affected her poop schedule?
fwiw she's not in daycare and we're home a lot, so she definitely has plenty of opportunity to poop, especially in the evenings. I don't want her to get in the habit of it but I'm not sure what to do.