Looks authentic to me, but I would want a fuller descriptiion of the authentication process. The fiber analysis is only as good as the authenticator and I would like to have seen Fonda Thomson's name used or an equivalent (if there is one). My initial impression was that it is most likely an Arkansas flag (the ninth state to secede, and they were pretty big on first nationals in their presentations to the companies) with the larger center star representing Arkansas.
The price itself is an indication of its authenticity. E-bay flim-flams generally start off around $1500. Obiviously a serious seller, but a flag without definite documented history, as is this one, will not go into six digits.
I like it.