@High kev ..... I'm sure there have been "incidents" where shit went awry 'cus "Shit happens".....but I honestly only remember one bust concerning seeds...prolly 15-20 years ago. They were already watching the folks for a suspected hash oil lab...and the seed send was the probable cause for them to get the warrant and bust down the door. Couldn't find the article. Too many clowns getting busted for manufacturing oil and lots of stories on that...but nothing specifically mentioning seeds...nor could I find the article for that particular incident.
My guess is that the real threat for being a seed maker would be your plant count. Takes a few plants to really do it right/at a retail scale.....and most guys are speeding and at risk in that light moreso than sales/etc......but if they put 2 + w together and yer doing both....and have associations....those Conspiracy to Manufacture charges (not going away cus it's now "legal") can be rough and carry serious time. "Legal" means no sales....at least here in CO. Seed sales will net you the same charges as selling bud....and worse cus of the tax gig.
And very few folks will grow/want seeds. Most are gonna head to the shop with the cheapest prices and best selection....and if they let em sell seed...yer out once again. Not gonna go to jail for personal here though......and if you have personal...you don't need to worry much about the boys in the money game. It's easier now than ever.....and most didn't jump on the wagon until it was "safe".... so no sympathies here...LOL.