Man, that'll do it. I dug my own fence posts last summer and now I'm picturing them just tipping over like dominoes. I used way too much gravel and not enough concrete, so my whole backyard is basically a giant wish at this point.
So when you say you used way too much gravel, what was your actual mix? Like, were you just filling the hole with loose rock, or did you tamp down layers of it with dirt in between?