If you read Andreas Moritz 's latest book he discusses having stones after just doing the enema. I have also experienced this, towards the last of the water that comes out, I have had stones, hours before even taking Epsom Salts . I thought it was the salt water flush that he recommends, but alas, my last flush I even had them with my morning spring water enema on flush day, 8 hours before taking any of the flush ingredients. I'll have to take another look at the book as I don't remember why he said this occurs.
I also had some stones after drinking literally a gallon of apple juice a day but that was before my learning curve on all this changed, best results come from doing the exact flush protocol.