Mason... years ahead of Zander in potty training??

On Tuesday around bedtime, Mason took off his diaper like he does most nights in preparation for a diaper change and new PJs. Only this time, he said, "I have to go potty" and ran into the bathroom. We just laughed thinking he was cute copying the actions of his big brother. When I peeked in the bathroom, he was on the step stool and putting the seat up. He then stood there for a few minutes. Every time I would come in there, he would say, "go away mama!" So, I gave him his space peeking every so often to make sure he wasn't doing anything naughty. Then, all of the sudden I heard him peeing! In the toilet! Holy crap! I ran in there (I think I scared him) and said, "good job Mason!" and gave him a big hug. I could tell that he was very proud. I was still in shock. Zander didn't even pee once in the toilet until he was 3.5! And here my 21 month old independently used the toilet. I figured it was just an isolated incident until last night - he did it again! I always knew that he would be potty-trained quicker than Zander - just a personality difference. And hopefully it will be sooner than I thought. I'm not going to push him. I'll just keep letting him try when he wants. He likes to copy everything Zander does which is where this is all coming from - I think. Regardless, I'm cool with it!