i think its fairly normal to have a slight temp jump during AF!, MINE doesn't it just goes down gradually....lol, but ive heard of ladies that do have slight temp increases, maybe you could do a test just to be sure ur not preggie and it wasnt late implantation?
also, ff usually estblishes ur coverline when it pinpoints ur ovulation....basically ur coverline is calculated by counting back from ovulation (6 temperatures) out of those 6 the higest temp go up by 0.1 degree and thats ur coverline, shouls be accurate unless u have an anomoly, which is an out of place temp, either too high or too low, ff discounts these!
so, u can easily calculate ur own coverline, once u get the three high temps that indicate u've ovulated, just do the counting back 6 temps from ovulation thing...you should see how ff calculated it then!