It's pretty typical for Priority shipping, I think if you wanted to do it up special there is a priority box that fits inside another Priority box that still makes room for padding. Not always necessary, I even had one recently double boxed like that recently that still got "damaged" with no signs on the outer box, which felt fishy, but benefit of the doubt kind of thing.
In short, do they best you can within reason, and know that anything can basically happen but to be able and say, "you did all that you could do!" It goes a long way