For dual thread CN mining to keep its highest hashrate over time you need to make sure the two threads are running with the appropriate separation in time. If they gravitate and become too close to running synchronously, the whole point of running dual threads disappears. Therefore, it's better to delay one of the threads a little before starting the next hash run. This is the "interleave adjustment" logged above. As long as your hashrate is stable (and high) over time, it's nothing to worry about, everything is working as intended.