The oh shit notes and the smiley faces were not part of normal customs operations. That a customs agent could have been taking them at first is a real possibility. The notes and smiley faces seem to have stopped, but when they started showin up in packages is when this all started.
Certainly it is a possibility, but i do not personally consider it as an issue in any way. Authorities have often been caught smirking or making snarky comments. If i was bored and found some seeds, id have considered putting a smiley face on it. It's not as if they discovered a pound of uncut cocaine. In any corporation there is more leeway with regard to actions when it is an item of insignificance. Customs probably couldn't give two damns about intercepting seeds, but the law and their superiors demand that they do. Intercepting seeds will do absolutely nothing to change the amount of pot grown, and everyone knows it. It's purely protocol.
At the end fo the day, noone knows anything, so my argument is no more or less valid than yours, i just don't personally see it as a viable argument. I don't even know how people decided to relate a smiley face in their packet with the seeds being stolen.
Heck, one could argue that they put the smiley face instead of a customs notifications so as to make it harder to get a re-ship. No different to people stating what stealth they paid for, they then go out of their way to vividly explain the procedure for getting the seeds re-shipped. One would have to be an absolute fool to think that people or machines are not employed to look out for these kinds of discussions. "hey, just take a photo of X and the tude will reship", so iff the authorities read this and chose to act, they simply change the way in which they take the beans (why should they bother informing you with an official notice that they took your seeds, you're not about to pipe up to the police about your seeds going missing and there not being such a letter) and you no longer get a re-ship based on the companies present policy.
sorry, but i think that the notions of customs agents stealing seeds for themselves is just absurd.