Japanese Red Maple seedling, needs some help

[in(cense)]

so my friends dad gave me this Japanese Red Maple seedling from his garden (he knows im into plants and for some reason so many of these trees grow around their yard) and it looked from what i could tell ok. i looked it up in my book and i read that they do best in a moderatly shaded spot while still getting sun, i asked my mom and she thinks its just shock, im thinking it'l need some quality soil, maybe an actual pot (while keeping it a small one) and maybe a lil time to adjust, but i noticed when i just went outside that the leaves where turning downwards mroe than they were this morning, so i brought it inside into a room in my house that seems to be very good for growing plants in, in the pictures ull see many of my mom's tomato plants that she starts each year in this room, and ive had other plants that've been in there for years and still are that have grown tremendously.
one side shot of the seedling:

another one:

the drainage holes at the bottom of the Dixie cup that it's in(the soil drains pretty well and the holes seem to work):

the window where the light comes from:

a full-view shot of the tree in the cup, its on the floor just for this shot:

[Gnome]

in(cense),

I don't see anything that seems out of the ordinary. This was just potted, correct? If so I think I would not be too anxious to do so again. If this is in regular potting mix be very careful not to over-water it. Get it back outside tomorrow in a sheltered spot, it does not belong inside.

Norm

[in(cense)]

aight, ill put it back out tomarrow
it was potted yesterday, so yea i guess it'l b ok for a while.
its not really a soil mix, this is the soil taht was in the ground where it was origionally growing, it wasnt intentionally planted, my friend's dad thinks it came from anoter Jap. Red maple thats just near where it was growing, so again it's in the origoinal soil from the ground where it was growing.