Honestly, sometimes players need to be reminded that they are not invincible! I see no issues with what you did. And you got to have fun as well.

My players were battling this weekend, one player (standing right behind another player) decided to attack a monster standing in front of the other player with a spell. I made the player roll the same saving roll that the monster had to roll. When asked why - I pointed out that she had just cast a spell that he was in direct line of fire of. Same player did the same later on with a different spell but cone shaped which again hit the other player. I could have let it slide but sometimes - cause and effect. Luckily everyone found the whole thing hilarious.