Why did my cycle length change? LONGER UGH

This month my cycle was predicted to be 34 days long on Premom and Glow. Right now I am on day 37 and no signs of AF, I don’t feel pregnant at all though so I’m just feeling it’s a late period. My cycles are normally 30 days long on the dot. Why did my

Apps predict I would have a longer cycle this month? Is this right? Any answers would be great 😊