If you had said your results were based upon the Daily or 4H time frame, I would say the results were skewed due to the ES being in a straight trend for the last 6- 7 months. June was a lot more choppy, but this was balanced by wide daily ranges. If you're trading off one second charts the system should surely cope with most conditions.

I would keep going with it and record as much as you can regarding market condition, session and daily ranges. If it fails you should be able to see what has changed and make the necessary adjustments.