Clean your fingers and don't touch the seeds before touching the box. Find a way to keep your fingers uncontacted and then don't touch the box with anything that has come in contact with them.
Mine came back in a trunk with all my gear when I demobbed. there was a cursory APO inspection and later before it was palletted they walked the dogs over it but they were just sniffing for bombs.
Shiiiiieeeeet.. You better send some of those mothers to me, goddamn it. Haha. But, shit, man.. That's a lot of seeds to figure out. And 400's going to be mad dank. So, definitely seal that mother fucker in something.