Although construction and properties of DFA are well known in the theory of language and automata ([8]), their connexions to pattern statistics have surprisingly not been extensively studied in the literature. In particular, the strong relation presented here between the FMCI technique for pattern and DFA appears to have never been highlighted before. If this interesting subject obviously need to (and will soon) be investigated more deeply, it is not really the purpose of this article which focus more on the algorithmic treatment of a built FMCI.