Jack vs. The Potty

So, everytime I have suggested Jack using the potty he refuses. At first I thought it was a boy/girl thing since it seemed he would do it for daddy. Well, I was wrong... It's more of a Jack do it himself thing. This morning I was working on getting Jack dressed and before I did the phone rang and I ended up talking for a bit. I was sitting in the living room upstairs when I noticed Jack going into the bathroom. I decided to wait and see what would happen. After a few minutes he emerged and proudly told me he went pee-pee on the potty. Sure enough he had. So this afternoon I let him run free of clothing and sure enough I noticed him run into the bathroom. I decided to wait. Then I heard the toilet flush. Jack again came out and said "mommy, I went pee-pee" Of course, I was excited and went into the bathroom and asked "where did you go?" Jack proudly held up one of his bath nesting cups and said "in here."