We had a concrete patio poured on Saturday and on Monday morning small black holes - 1/8" to 1/4" appeared . They appeare to be surface stains and have an oily substance in middle. The cement company said that it was something in the sand base. The patio company said that it had to be something in the cement truck. Oh and they both said that they had not seen anything like this before. Live in South Louisiana. Does anyone have an answer or seen this before?