Blogger seems to be doing something odd with comments. Some of the comments appearing in the 'Recent Comments' section on the front page don't show up on the post in question, and don't get emailed to me by Blogger as all other comments do.
I've noticed this for with recent comments from Eric Olthwaite and Tim Selwyn, and Tim said he lost another comment when Blogger went down recently for half a day; some friends have told me too that Blogger just refuses to let them register to post comments. Sheesh. If I knew how to, I'd set up my own stand-alone blog site with a reliable host (this, BTW, is an invitation for volunteers).
In the meantime, you might like to be careful when you post comments; copying your comment to the clipboard before you press 'Submit' would be one suggestion.