I have seen my hair get darker after two months of Finasteride and Rogaine use. Am I having a position reaction?

Yes, it means that your hair getting stronger, thicker and healtier and anagen phase/growth period of the hair follicles start to increase.

One of the primary responses to the use of finasteride and minoxidil can be a vellus to terminal transformation, meaning that the very fine hairs thicken into larger, stronger strands.  These strands ofter have much darker color - a great sign you are getting a your hair to grow in!! Great work! 

That has been our experience. Darkening of hair in males with AGA is generally a positive sign. Continue to monitor this as a variety of factors can also influence transient hair colour including medications, ultraviolet radiation (...and of course hair dyes).

If your hair was miniaturized and it became darker, it probably is reflecting a reversal of miniaturized hairs which often lose pigment.