You can't worry about temps dropping a tenth of a degree or two. It's all about the whole "range" of temps. My temps will go up and down from about 98.1 to 98.4 the whole LP and you can't worry, as long as they stay within that range of temps.
drop can mean anything: AF is coming or ovulation dip or today in TX we had a cold snap (i.e. 60 degrees :)
I think you can only interpret BBT looking backwards but not forward. Temps going up or down can mean anything. Don't read too much into this. Besides, a temperature