Im brand new to cycling with a brand spankin new bike that I just got yesterday. I have rod it for about 7 miles, total. Today, I noticed my handlebars had play in them (up and down). They were good and tight yesterday, but have loosened some today. Is this normal? Just tighten them up and keep going?

Bolts coming loose is not uncommon. Yes indeed, tighten them up.

Is it the handlebars or the pivot on the adjustable stem that's come loose? I'd guess the latter. If the problem is not a loose bolt, that should become evident when tightening bolts doesn't fix the problem.

No; bars (all components) should stay tight when riding, this should have been sorted in the pre-delivery inspection (assuming you got it from a bike shop) as it wasn't if not, take it back and get them to fix it.

If you got i from a direct supplier, would still be worth taking it to a real bikeshop, to find the cause of the loosening.

They did a pre-delivery on it. It is loose at the hex nut where the handlebars sit on the stem.

So they missed that one, would take it back, and get them to check that, and any others they missed.

Yeah, Ill ride it up there and have them fix it.

Tighten each bolt just a little at a time and go in a criss-cross formation (upper left, lower right, upper right, lower left.)

Make sure the gap between faceplate and body of stem is the same top and bottom.

Or just roll on up there if it ain't too much trouble.