S.Z.
I have 4 kids, and all of them went through the stage of chewing and then spitting out. I think they just wanted the taste of the food, and didn't understand that their body needed it for fuel. If they're otherwise happy and have energy, don't worry too much. But, keep explaining that spitting is rude, especially at the table, and explain that they have to SWALLOW for the food to make it all the way to the tummy. Good luck!