Its an assumption based on what little information was available, I said IIRC because IF I am remembering it right the person said something about being out on a run/practice or getting back from the gym and going to take a shower.
I will have to play through again to refresh my memory but that is what I remember, seeing as the Mom is the principal I doubt she would be taking a run or going to the gym right after work.
Sorry if you thought i was saying it as a fact, IIRC usually indicates an assumption based on memory. Which taking the MC into account is not always reliable