I don't believe the discoloration is from moisture damage, the box is not puffy or crinkly like it absorbed any moisture. When I was helping my friend throw out some of his step father's stuff after he died, I saw this among the pile of electronics stuff, way up high with like a kid's easter basket on top of it covered in dust. The shape of the light part on the top of the box is the shape of the basket when I lifted it off the top. I can only imagine it had been there for decades. My friend's mom wanted all that "junk" thrown away....so I gave them some money for the Vectrex, some other Texas Instruments stuff and some Coleco Vision & Atari games (the boxes on the games are in pretty bad shape, unfortunately).
I didn't know what the sticker on the box was for, I thought maybe it was my friend's mom....her name is Karen, which is written on the sticker. I thought maybe she worked at JC Penny or maybe it had been on layaway or something.
Thanks for the advice on everything, I'll definitely leave it sealed.