We've had a few batches this year that have come out with a red hue. When I put them in the line-up of our grade kit, it's hard to tell what to grade the syrup because it's not what I would call darker than grade B, but it is definitely more red. Has anyone run into this? I'm wondering:

1. How do you determine the grade of a syrup that is off-color?
2. What might be causing our syrup to be red?

We do have a variety of types of maple, including a number of soft maples, tapped. I'm wondering if this could be playing into it?