Blogger is evil.
I have moderation turned on for old posts to stop the spambots. If I get a comment that needs moderating, Blogger Emails me the comment with a note to do something about it. All comments eventually get released unless they are obvious spam.
If Blogger's spam-machine catches a comment, I get that comment by Email as normal but with no indication that it's in the spam bin. As far as I am aware from the Emailed comments, it went through.
So if you get caught by the spam-monster and it takes a while to show up, that's because the damn thing hasn't told me you're in the sin bin. I only find out when I check in there or if I look for your comment to reply.
It seems to randomly pick on people. I haven't found the logic in it yet. Maybe there isn't any.
Maybe it just has targets to meet.