Alot of stories? I'm pretty sure there is only one
And no you shouldn't be worried. I believe that might of been a bit of a freak accident. You are using gravel meant for fish tanks and I've had gravel for years that is smaller than a pea. It is probably better to go for bigger gravel to avoid those one in a million chances. So if you are really freaked out, try to find bigger gravel. However this may be more trouble than it is worth as the gravel holds alot of the good bacteria in a tank and changing all of the gravel may destory a cycled tank.