What usually gets people, and what a lot of people don't understand, is all it takes is for you to touch some bud and then touch any part of the package. Seeds must be double vacuum sealed with a moisture barrier bag seal around the outside. After the first seal, everything should be done in a room which does not come in any contact with weed or weed smoke, period. After the last seal is put on it must be dipped in or rubbed with rubbing alcohol to get any residual weed molecules off of it. When I was on Grateful Dead tour in the 90s, I saw many people get busted by having their sheets of acid sniffed out by dogs because they had touched it with their weed coated fingers.
Edit: saw it once, heard about it much more.