F.Y.E. in store help?

Ok so i like F.Y.E. a lot just because they are one of the few stores besides pawn shops that sell used cds and movies and stuff. I’m 16 and ive gone to trade in some of my used cds a few different times before and have had no trouble at all getting them sold to F.Y.E. and getting store credit on a gift card. But i went yesterday afternoon and took some more of my cds in there to sell and there was an older dude in there and he said to show him my cds and so i did and he asked me how old i was and i said 16 and he said you have to be 18 to sell things there. He told me to ask the other lady working there if she would buy them instead but she wouldnt either. Whats up with this 18 and over rule? Did they just start this thing or does it just depend on who you get working in the store because like i said i’ve never had any trouble trading in before and i never saw an "only 18 and over can trade in" sign anywhere it just said sell and trade in your used things?