The first thing I wondered was why did you wait a year to do another flush? With positive results like you got last year, I would have flushed until I saw no more stones.
I know each time I flushed, I experienced something different. I saw different sizes of stones, different colors, etc. My first flush, the first thing I saw was a long, green rope. But, every flush for me was different.
So, maybe since you were expecting the same stuff you saw the first time you flushed, it was surprising to see what you saw this time. But, my suggestion is to just be happy you got that stuff out of your body!