I think it won't be a problem. In the sticker in the US pport the name is printer as First middle last, all on a single line. In the booklet however there are 2 sections one for Last and one for Given. So the booklet will have your last name blank. But then the visa sticker is the most imp, so no problems I think.
If it bothers you and you haven't mailed the packet yet, just fill another form all over again.