Mucus in the poop is definitely worth a call to the doctor.
It could be the balls from the nappy, I’ve had a few before when LO’s nappy is full
Apart from that stool did it happen again ? Maybe the morning nappy was too full and the lining came apart if it hasn't happened again it could have just been an overfull nappy But if you found it in all the nappy since then I would seek medical help
Take a photo of it to her doctor.
probably is nappy filling, i find the odd one here and there every now and again
I’ve never seen or heard of that, but it sounds like something to discuss with your medical care team.