So what? MM specifically asked her parents at breakfast why they hadn't come when she and Sean were crying the previous night. McCanns have a definite routine at night with the children which included leaving the door ajar 10 cm to allow a glimmer of light in. GM checks finds door half-open. His only explanation for this is MM up and about but finding her in her bed (or so he tells us) he returns the door to its rightful position but doesn't say to KM 'I don't want to alarm you but I think MM may have been up and about as the door was half open, she's in her bed asleep now. I'll go back and check all is ok again shortly'.
Sometimes being pedant assists those who can't, don't understand plain speaking.
GM notices the door has moved- he may suspect MBM was awake at some point, and may have wandered to toilet,parents room.where ever, he check to see his daughter on top of the bed exactly like he left her as it was a warm evening. he moved the door back to its original position. no more to be said? well I think so.
1. when he saw his daughter as he left her- who moved the door?
2. If he thought his daughter was up and wandering around - she would have been faced with the same plight as the previous night- all three of them alone and no parents around.
3. would she just climb back into bed to the same position, as the temperature is an issue here, or go back under the covers (where her mother claims she left her all snuggled in because it was cold)
4. OR would she go out via the patio door to look for her parents and disappear?
The devil is in the detail.