Is this my error or Bobby's?

Hi

Bobby marks down the following code for a Priority 2 Accessibility failure to 
"Nest headings properly." It's a violation of WAI checkpoint 3.5.

 	<h1>1. Primary Heading</h1>
 		<h2>1. Secondary Heading</h2>
 			<h3>1. Tertiary Heading</h3>
 				<h4>1. Quaternary Heading<h4>
 				<h4>2. Quaternary Heading</h4>
 				<h4>3. Quaternary Heading</h4>
 			<!--
 			<h3>2. Tertiary Heading</h3>
 			-->
 		<h2>2. Secondary Heading</h2>
 			<h3>1. Tertiary Heading</h3>
 			<h3>2. Tertiary Heading</h3>
 			<h3>3. Tertiary Heading</h3>

The problem, according to Bobby, is with the second <h2> heading. However, 
when I uncomment the <h3> heading above it,  run the code through Bobby 
again, it gets a triple-a pass.

I'm afraid I fail to see how the original outline is at fault.

Thanks,

Seth

p.s. sorry for the made up word quaternary.