Here's the deal. If someone says "What I am saying right now is false", you get a paradox: assuming that he's telling the truth leads to the conclusion that he's lying, but assuming that he's lying leads to the conclusion that he's telling the truth. Both possibilities lead to contradictions; that's what makes it a paradox. With the Cretan's statement in the post, there is a possibility - the one I described - that doesn't lead to a contradiction, so there's no paradox.