I noticed that my betta, Nelson was holding his mouth open like a big yawn. Only he held his mouth open much longer than a yawn. Then he sort of stuck his gills out a few times. He wasn't flaring; he didn't move his gills completely out and he didn't use his fins. After he did this a few times, he threw up/spat something out that looked like a piece of chewed up food. This was probably at least two hours after I fed him his usual three pellet breakfast. This was the first time I've noticed him do this. Should I be concerned?