very large initrd.img for newly compiled kernel

I just compiled the 2.6.31.6 kernel for my iMac (as a test run for the mbp), and it seems to work (except that apparmor doesn't load, which is one reason why I am currently not booted from it), but its initrd.img is 50 MB large, as opposed to only 7.4 MB for the regular kernel. Is that normal or did I add too much stuff in make config? Even if I did, which is likely, the difference shouldn't amount to that much. I used make oldconfig, so most of the options were already given. I trust http://kernel.org, so I installed without verification. Should I rather use a mirror? And where can I find understandable info about gpg? The kernel.org page is not exactly clear.