RedCloth 3.0.4 parses badly some input

[wejn]

$ irb
irb(main):001:0> require 'rubygems'
=> true
irb(main):002:0> gem 'RedCloth', '=3.0.4'
=> true
irb(main):003:0> require 'redcloth'
=> true
irb(main):004:0> RedCloth.new("84 m^2^ + 10 m^2^ terasa").to_html
=> "<p>84 m<sup>2^ + 10 m</sup>2^ terasa</p>"

$ irb
irb(main):001:0> require 'rubygems'
=> true
irb(main):002:0> gem 'RedCloth', '=3.0.3'
=> true
irb(main):003:0> require 'redcloth'
=> true
irb(main):004:0> RedCloth.new("84 m^2^ + 10 m^2^ terasa").to_html
=> "<p>84 m<sup>2</sup> + 10 m<sup>2</sup> terasa</p>"