I concur with a1fox3 that there appears to be a statistical link between the number rolled to get to a gold or other box, and its contents.
In an unrigged game, there shouldn't be such a link - any box opening should be independent from the die rolled to get there. This is for me what I take issue with.
And no, jacopo hasn't got the slightest idea about statistics. He's not the only one, though.
I actually start considering statistics specialised knowledge in this day and age, so we shouldn't hold the fact that they don't understand any of it against people.