6 year old molars at 5?

This morning Tyler had been complaining his tooth hurting, I was on our way to school so I couldn't look at it until we got to his school. I stopped the car and tried to look and without proper lighting I really couldn't see anything. I thought maybe he had just had a chip and maybe the chip cut his gum, or maybe he bite himself. I didn't really worry to much about it. Then tonight I was flossing his teeth before bed and he started complaining again, telling me that I was hurting him. I was in better light and I could get a better look and way in the back is a cusp of a 6yr old molar starting to come through. I could not believe it. I told him his getting a BIG BOY TOOTH, He was so excited he could not wait to tell his daddy. He's only 5 not even 5 1/2, he was always early at everything. He got his first tooth at 4months and crawled at 5 months and walked at 8 1/2 months ran at 11months and started claiming everything he could 15months, so its no surprise that he's still doing things early. lol