I have 3 tiger salamanders, They have stopped eating for at least a week if not more before. I have had them for 9 years, it used to worry me, but they are still going strong. I know they are not the same as yours, but Most don't need to eat often, they can go a week or two without eating. They can easily be stressed, temp., movement, etc. which will make them not eat. If he still looks healthy give him a couple of days he should eat again.
I have one who wants to eat all of the time. One nightcrawler after another. The other two only eat every couple of days at most.