Of course it's important!

Two children that are normally friends were having a very heated discussion in block center this morning.  It started out fine; they were playing nicely and using kind words with each other. They were both engaged in the materials.  Suddenly their voices got louder and one of them got so angry, she hit her friend.  If I hadn't intervened, it would have turned into a fist fight.  What was so important?  They were arguing over whether a horse said "Neigh" or "whicker."  I'm sure we all wish our problems were so small!