Another old one that you hear relatively commonly in St. John's but it certainly isn't the most popular way to express the same sentiment:
"Good job", in this context, means something in between good planning and luck.
It St. John's, it leans a little more toward planning than luck, and you'll still hear it today in phrases such as:
"It's a good job we left when we did or we'd've been stuck in traffic."
"It's a good job she left him before he got on the coke."
But in the context above, I think people from town would be more likely to rephrase the sentence and use "I was [best kind/just grand], sure, with the seaweed to protect me" instead.