I`ve had dogs that have done that...one dog that springs to mind was our big bear of a GSD Duke, he would refuse to eat for seemingly no reason and it was both maddening and worrying at the same time. Once we added other dogs to our family he was fine, he knew if he didn`t eat it one of the others would!.... Oh, and Bob, how could I forget how fussy Bob used to be when he was a pup, even up to a few years ago in fact! Besides all the picking the bowl up after five minutes and other stuff like that I went through numerous different brands of food, tried wet food, dry food, adding titbits, you name it I tried it. And then he just seemed to settle down gradually and accept the brand he has now. He will still hold out for a while for some nice titbits now and again, but his bowl is always empty by bedtime!
The bottom line that I have learned is what everyone else has written, as long as it doesn`t go on too long and he is otherwise ok, don`t worry about it!