Strange behaviour with Prawn

prawn-oddness.rb

require 'rubygems'
require 'prawn'
pdf = Prawn::Document.new(:page_size => "A4", :page_layout => :landscape)
pdf.bounding_box [0, pdf.bounds.height - 40,], :width => 740 do

  # No Entries
  #
  pdf.table([["Total Value of Spend", "Total Transactions", "Average Transaction Value"], ["4558.5100", "30", "151.95033333"]], :header => true) do
    row(0).style(:style => :bold, :background_color => 'cccccc')
  end

  pdf.move_down(10)

  # Works
  #
  pdf.table([["Total Value of Spend", "Total Transactions", "Average Transaction Value"], ["4558.5100", "30", "151.95033333"]])

  pdf.move_down(10)

  # Works.
  #
  pdf.table([["Total Value of Spend", "Total Transactions", "Average Transaction Value"], ["4558.5100", "30", "151.95033333"]], :header => true, :cell_style => { :borders => [] })

  pdf.move_down(10)

  # Suddenly Works
  #
  pdf.table([["Total Value of Spend", "Total Transactions", "Average Transaction Value"], ["4558.5100", "30", "151.95033333"]], :header => true) do
    row(0).style(:style => :bold, :background_color => 'cccccc')
  end

end
pdf.render_file('test.pdf')

Removing the Bounding box solves the problem