Heading tags in the story leaks into the table of contents

[ccsenter]

I have an mdx page rendering stories from an attached story file. Some of the stories have heading tags h2, h3 in it and these will show up in the side TOC.
The documentation says: "By default, the table of contents will ignore all content placed within Story blocks"
The stories in my MDX page are rendered in blocks of

<Canvas of={...}>
     <Story of={...} />
</Canvas>

Should I do it differently?