In Liz Castro's Epub Straight to the Point (at
her blog) she mentions this bug and suggests enclosing the text of the <p>...</p> within <span>...</span> -- so you end up with <p><span>...</span></p> -- ugly, but it's a bug. It's not clear to me whether the text-alignment goes with the <p> or the <span> though, so you may have to experiment. Buy the book and the extras, they are well worth it.