I thought that a cop couldn't proposition you for a drug sale? Usually on stings they have a 'dealer' look like a drug addict and use general terms, and wait for the seller to come up to the under cover cop. If the cop out of no where, had no idea you grew anything, asked you if you wanted to buy some clones or seeds, sounds like entrapment to me, but what do I know I'm not a lawyer.
Then again there is no saying that he doesn't work for the cops, but isn't one himself. Maybe he got busted and in order to get himself out he has to rat out like 5 other growers or something, that stuff happens. And a growshop that keeps a list of who they sell clones to, makes sense to me if you are crooked. It's your get out of jail free card. "You want to bust me for growing 20 plants? Well, if you let me go I'll give you the list of 50 people I sold clones to over the past 4 years." The cops get more people, the hydro store owner goes 'free', and few people would expect their hydro owner to be ratting them out, after all it would hurt their business if you got locked up.
All and all, too suspicious. On the pro side, you get some sweet clones, on the con side you do serious time in jail ..... in that scenereo the pro hardly outweighs the con.