Independent 2-year old

Why is it that when you ask a 2-year old to do something, he instantly says "no!"? But when it's him suggesting the same exact thing 30 seconds later, he is all about doing it. One example - We ask him if he wants to get dressed to go outside and play" (which he LOVES to do), he says "no." Wait 5 seconds and now all of a sudden, he is telling us that he wants to get dressed so he go can outside and play. It's almost like it has to be his idea. If it's not his idea, then he doesn't want to do it. He has been saying this a lot lately and it is driving me and Jeff crazy. At first it was pretty cute, now it's just annoying. I guess he is just showing his independence. Is this the beginning of something bigger? I have a feeling that Jeff and I better just get over this because there is worse to come - at least that is what I am sure my mom wished upon me!