I just started tracking my temp with a brand new BBT thermometer that says accurate to 1/10. Yesterday I woke up at 7:30, my temp was 98.whatever. Today I woke up at 5:30 and it said 95.something. So I retook my temp 2-3 more times (all within a minute) and they were all different. Is that normal for my temp to be so low and rise so quickly after waking up, or did I get a faulty af thermometer?