I have heard of some examiners being extra critical of people with low scores. Just because a 72% is passing for the certificate/rating, it doesn't always look the best to the examiner. Generally from what I've seen, if you get a 80% of higher, you should be in good shape. From 70-80%, while maybe not a retake but just besure you can answer those questions really well. Although, some examiners could care less about what you got, even if it was 70%.