I'm just guessing, but are you just tapping the spacebar? If you hold the button you get way more height on the jump.
It's very likely just me (since I kept getting very close) because I simply can't do fast and precise at the same time consistently. I would almost guarantee that a frame-by-frame would show that I'm pressing the key very inconsistently with regards to timing.
In all seriousness, I would say to wait and see if you get any complaints.