Mucking the Straight Flush

Last night I flopped a hearts flush with middle suited connectors, bet it and got a call. The turn was another heart, yuck. But wait, it was the 7h, giving me a 9 hi straight flush. It also gave Pete a set of sevens. Forunately for him and unfortunately for me the board did not pair and he folded when I bet out on the river. And what did I do? I showed the hand. I've always said that it's so weak to not be able to toss huge hands like that into the muck when your opponent folds on the end. Today I got my chance. This time I flopped the straight flush, bet it out and my opponent folded. No hesitation, hit "You win, muck cards" and that was that. Unless I have good reason to I'm never going to show 4/kind or better from now on.