I don't know Linda's signature very well but looks ok from what I have seen in the past. I have met the dealer that you got this from he is an very nice guy and does alot of private signings from what I recall. All the autographs I have seen from what I know of have all been good. Hope that helps you out.
Thanks very much for the info on the dealer. I do think it is genuine myself, as he said he was selling off some of his own private collection. Good to get input from members here though.