Wouldnt worry and would stop charting. I know the experience of the miscarry can make you analyze every detail, but I dont think your chart is going to be the first sign of a miscarriage. Isnt it your progesterone that makes your temp high? My progesterone varied throughout my first trimester and once had a 10 point drop. 14 weeks today and my baby is doing just fine.
Hopefully someone with pregnancy charting experience can chime in, but I really wouldnt worry about the temp drop.
Meg, Momma to Joey (Feb 2010)