Feet on the floor. It’s quite common. I usually get it on a Saturday morning. I get up but don’t do breakfast for ma6be another hour or so. I usually have a small amount of bolus to cover it.
You get out of bed and with the absence of food and insulin/ bolus your body / liver decides to supply energy to start you off for the day.
Eat breakfast and take bolus on rising usually prevents the occurrence.
It's a well-know effect, experienced by (all?) T1s. It's called the Dawn Phenomenon, it happens when the liver dumps some glucose into your bloodstream; because you've been fasting overnight and it's your body's way of giving you an energy kick.