Steps to reproduce

(Perform in Confluence version older than 4.x)

1. Create page 'A' and page 'B'
2. Insert Excerpt Macro with content: 'This is page A' 'This is page B'
3. Add label 'sample' on these pages
4. Save page 'A' and page 'B'
5. Create page 'C'
6. Insert Content By Label Macro to display pages with label 'sample' and tick the box 'Display Excerpt'
7. Save page 'C'
8. Upgrade Confluence to version 4.3.6 or 4.3.7
9. Go to page 'A' and edit the excerpt: 'This is page A being edited'
10. Save page 'A'
11. Go to page 'C'

In the page 'C', the excerpts are being rendered differently. Excerpt from page 'A' is rendered in new line but page 'B' is rendered in line.