True - but then again repeating something you know how to do because you failed at a different challenge isn't really increasing difficulty :D
I think it depends on the genre: in a puzzle-stealth game the repeated skill checks are kinda pointless and frustrating - you wanna find out how to do the current puzzle not repeat the old one. In a more action based stealth game repetition improves your skills so you should repeat the basics often,
Whatever - minor point. Game is great - good job :D