When upgrading from FreeBSD 6.2 to FreeBSD 6.3 with freebsd-update (detailed here) and using a custom built kernel, there is one extra step to be fully upgraded. After you follow the three steps from the instructions and reboot for the second time, you will be unpleasantly surprised to see that you are still using a 6.2 kernel. In fact all you need to do now and go rebuild your customized kernel, install it and reboot. Now you will have a customized 6.3 kernel installed.