XPATH indices different?
===

I am using Mechanize on Ruby, and notices the following in my Ruby console:

    1.9.3p194 :188 > testpage = Mechanize.new.get "http://www.sis.umd.edu/bin/soc?term=201208&crs=AGNR"
    ...
    1.9.3p194 :184 > testpage.search("font[@face='arial,helvetica']").last.search("b[2]").text
     => "" 
    1.9.3p194 :185 > testpage.search("font[@face='arial,helvetica']").last.search("b")[1].text
     => "Special Problems:\nSpecial Problems;"

Why is accessing the second `b` element in XPATH giving a difference result than accessing the second element of all Nokogiri `b` elements returned giving a different result?