Keep tracking. That one incident of 70-102 pre and post meal is likely just do to the lack of precision associated with the fingerstick tests in general.
You'll have to track a lot to see patterns. I have done six sticks in a two minute period and seen numbers ranging from 86-112. It's just the how it goes with BG testing unless one is doing IV draws and a lab to run the numbers.
That's why you need lots of numbers over time.