This was brought to my attention by a colleague, Stephen Tang, so I’ll let him tell the story:
I found an obscure rendering bug in Safari 3 when whitespace or a line-break appears in the inline box with side padding in a floated right container. See this URL in Safari 3.x:
From the explanation given, Safari 3.x doesn’t show the padding-right inside the anchor when whitespace or a line-break is present inside the element at the end. Instead, it shows the padding-right on the outside, like it was a margin-right. The first example on that page does not have whitespace or a linebreak, so it displays fine.
In conclusion, make sure that the contents of the anchor tag are tight with the markup.