SSH RSA key fingerprint not what expected in TouchTerm (iPhone)

Hi,

I'm in the process of setting up an SSH server on my Mac Pro for access on my iPhone running TouchTerm. So far I've done the following:

1) Generated a 2048-bit RSA key pair on the iPhone in TouchTerm
2) Added the Public key generated on the iPhone to the Mac Pro's "authorized_keys" file
3) Generated a 2048-bit RSA key pair on the Mac Pro using ssh-keygen with default settings and no passphrase (as required for a Host key pair, according to the manual)
4) Turned on SSH access in System Preferences > Sharing, for one specific user only
5) Set up TouchTerm according to my Mac Pro's IP address (which has been static for a couple of years now, and I've checked it today, so nothing wrong there) and username.

Now, when I attempt to connect to the Mac Pro from my iPhone over Edge or 3G, my Mac Pro's firewall registers the connection attempt with the following:

Allow sshd-keygen-wrapper connecting from <IP ADDRESS REDACTED> to port 22 proto=6

In TouchTerm a host fingerprint is displayed - however, this fingerprint differs in its entirety from the fingerprint revealed when I run the following command on the Mac Pro:

ssh-keygen -l ./id_rsa.pub

I only have one key pair generated in the user account on the Mac Pro that I'm requesting access to from TouchTerm. The other user account has no key pairs generated at all. If I select "OK" in TouchTerm, it proceeds to ask me for my local key's passphrase, but I'm unwilling to proceed past this point as I don't want to connect to a potentially unknown host.

I'm loathe to believe I'm the victim of a Man in the Middle attack, so what am I missing here?

S.