Blue Cheese Worry - 35 weeks preg?

went 2 a friends house, she made food - sliced potatoes,with red peppers,carrots, onions,cream,milk all baked in the oven. She topped in with cheddar cheese,then for the last 15 mins of cooking she put some small squares of blue veined cheese on the top. Now, I said to her, "what cheese is on it" and she said, "Oh, there is some blue cheese, oh damn, why did I put that on?" but she said she only put some small squares on, and she could see where she put them on, so said if she gives me a bit, in between where she put the squares of blue cheese on, that would be ok as no blue cheese on there. I was EXTREMELY hesitant because I know how much I WORRY about things, I wasn't happy about eating it at all, but it was such a difficult situation because she had made it specially. Anyway, so I had some, but I was scared, I just picked at the bits of veg & potato,didn't taste any blue cheese. Just as I thought I cannot stop worrying about Listeria - wld cooking 4 15 mins have killed any Listeria?