I had something similar happen a couple of times. I described one of those times in a thread here about being called a bum by the clerk for buying lottery tickets.
The other time was closer to what you're describing. I was cashing in about a half dozen CA Fantasy Five tickets for replays (which you get when you hit 2 out of 5) and the clerk said (with the highest possible level of suspicion in tone of voice) to me, "These are all from the same day!" as if it were a capital crime (or capitol crime if I had been in Sacramento) to buy more than one lottery ticket.
Since there are billions and billions of lottery retailers here in SoCal, I just decided to not go back there again, but McGinn's suggestion of disarming them with a smile and good-natured conversation sounds like a great plan for at least testing the waters.
If that doesn't work, then you should go Michael Douglas in "Falling Down" on the place and just destroy every shelf in the store with a baseball bat while talking about how they are doing a disservice to the community.
Just kidding, but good luck in your lotto endeavors, and please let us know how it turned out with this particular retailer.