Was playing one of my own levels yesterday and I couldn't beat it. It was very, very early in the morning, so I wasn't at my best, but even still... Before yesterday I beat it plenty of times - I play my levels a bunch before I upload them. It involved pulling off a long jump from a music note block, which is one of my least favourite types of obstacles in a Mario game. Might go back and edit it.
I never found my levels too hard before, I always thought they were right in the middle and I think that's the kind of trap that isn't much fun.