Here is my regex solution if someone wants to do it a little more complex I guess.

lowwords = words.lower()
    if re.findall('\D[a-z]*\s\D[a-z]*\s\D[a-z]*',lowwords):
        return True

\D -start with a non-digit character [a-z] - match one of these in the range * - match 0 or more of the previous regex \s - any whitespace character