Date (UTC) Average speed Valid shares Stale shares Invalid shares Rewards
2018-11-05 2,847,327 kH/s 41,320,448 65,536 (0.16%) 0 (0.00%) 0.0020429242695680 LTC
2018-11-04 2,955,226 kH/s 3,883,040,768 13,008,896 (0.33%) 0 (0.00%) 0.1919814186106880 LTC
2018-11-03 2,928,277 kH/s 3,711,459,328 149,061,632 (3.86%) 80 (0.00%) 0.1834982606356480 LTC
2018-11-02 2,915,377 kH/s 3,826,556,928 16,957,440 (0.44%) 0 (0.00%) 0.1845490511183872 LTC
2018-11-01 2,760,212 kH/s 3,628,056,576 10,895,360 (0.30%) 0 (0.00%) 0.1763707143290880 LTC
2018-10-31 2,697,764 kH/s 3,546,873,856 9,748,480 (0.27%) 0 (0.00%) 0.1724241787617280 LTC
2018-10-30 941,662 kH/s 1,233,223,680 8,224,768 (0.66%) 108 (0.00%) 0.0599507027558400 LTC
Your stale rate on 2018-11-03 was abnormally high, but from the pool's side it's hard to tell why. What I can say is that this probably wasn't a pool issue, as other users did not experience an increased stale rate. It is possible that there was some temporary network issue on that day causing increased latency between your miners and the pool's servers. Another possible cause, depending on how your hardware is configured, is overclocking, which generally makes a miner's output more unpredictable.