The first fork I built had that crown, and it is doing the same thing. I know for a fact that I didn't get it hot enough and that there is probably not 100% filler penetration. Fork has been going strong like that for a number of years. I would at the very least mark the ends of the cracks with a fine point sharpie so you can monitor the cracks, and more idealy, I would retire the fork. If you keep riding it, keep a close eye on it.