Why hasn't he told me this yet?

Well, let's look at it this way: it is probably the same reason you are asking complete strangers to dig into your brothers motivation and come up with an answer for you that is in no way based on any realistic detail of your and his relationship. No one using Yahoo! answers (except your brother) will be able to tell you why he did not tell you first. So, it's the same situation. you wish he would have come to you and talked to you about it, so the best reaction is not to worry about why he didn't tell you and to ask him, just him, why he hasn't said anything. that will be a much more fulfilling conversation than you will ever get from any one of us random people trying to solve your problem. Often, things that may cause some friction in families are the hardest to tell to those closest to us. So, he is obviously worried about telling you he is transferring, for some reason, and you are concerned with asking him point blank. open up the communication and you will feel much more in the loop with his decisions and those affecting your life.