Yes, you are correct. If you look above Box 4, in Box 3 it says "If born after 1998 and the child is younger than you... skip line 4a and 4b; go to line 5." (Please see the screen shot below) The print is a light blue so easy to miss.
In your case, box 4 should be skipped.
Your paperwork was filled out correctly.
Thank you for your observance and alerting us to what you thought was a potential problem.
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