The brown stain has to be important as to what really happened in case she was found.
"It is now my belief there was somebody either in, or trying to get in, the children's bedroom that night (2 MAY), and that is what disturbed them. The only other unexplained detail I remember from that morning (3 MAY) was a large, brown stain I noticed on Madeleine's pink Eeyore pyjama top. It looked like a tea stain.
At the time I just assumed it was a drink spillage that had escaped our attention, and that might well be all it was." (Madeleine)
"During breakfast the “crying episode”, already described, took place. She noticed a stain, supposedly of tea, on Madeleine’s pyjama top, which she washed a little later that same morning. She hung it out to dry on a small stand, and it was dry by the afternoon. Madeleine sometimes drank tea; nevertheless the stain did not appear during breakfast, maybe it happened another day, as Madeleine did not have tea the previous night and the stain was dry. (KM 6 Sep)