Ummm, since those are nearly polar opposite personalities, that's quite a change! Are you that Geiko chameleon?
IIRC, Meyers-Briggs is supposed to test for our default personality type, the one we are born with and deep down always are likely most comfortable with, though often as we go through life we develop skills and adapt to circumstances that can make us appear to be quite different. For example I am INFP(strongly I), yet most of my friends are shocked to learn that, considering me an extraverted greeter and party host. At some point I choose to be social and assertive simply because it was the best way to achieve what I wanted, but given a choice and circumstances am still most at home withdrawn into quiet research and quests.
Also at certain ages we tend to begin exploring other aspects/weaker sides of our personalities, becoming increasingly well-rounded(to an extent) as we progress through life. So our personalities can appear to change as we broaden our areas of interests. The order of this is different for each of the 16 types, but I can recall one example for INFP's: about age 30 we start to develop the 'S' side, with more interest in and appreciation for tactile things. Sure enough, I'm now far more interested in and tempted by fine food, the outdoors, and participating, rather than just designing and imagining.
Shrinkermd, is that about right, or is my typology memory rusty? Meyers-Briggs is a fascinating topic.