I'm not sure how it got reset, maybe it's because I updated my page count for more than 2 days? While I'm pretty good at updating my night reading the following morning, I updated my night reading for the past 2 days and that seemed to reset my streak - despite logging 2 other books on their respective days. I know it's not a big issue, but it motivates me to read daily and I was up to 70+ days!