This is nose wheel shimmy. First time it will be penned with an inspection and spin check - second or third time the nose wheels will be replaced which will cure the problem. It is very very common on 400s. I certainly would not escalate this as it is nothing and you would make yourself look pretty silly. I would think that it was put in the tech log once reported by cabin crew. The crew would not report this back to you as they have no reason to discuss the contents of the tech log with a punter - pilot or not.