Learn Texas Holdem

Question: I play weekly with some friends and recently we had an argument about a move a player made. Heres the situation, my friend and I were the only two players still in the hand and I said I was all-in. After sitting there quietly thinking for about a minute, he tosses over his cards revealing what he has. When I noticed this I immediately thought that meant he folded and I turned my cards over and started collecting the chips...he glanced at my hand quickly and nonchallantly called my all-in. He said it didn't matter if he threw his cards over or not cause he's just thinking whether to call it. But I took this gesture meaning that he folded. We immediately started arguing whether his gesture meant he folded and the pot was mine or I made a bad move by throwing my cards over. We played out the hand just to see who would of won it and he did.