I dont think so.both my school's Ib coordinator and the principal( who has been working with the ib system for 14 years) said that it'd be alright to take 4 at higher level and if i wanted to do anything else, i could get the certificate for it, but it wouldnt be included on ym diploma.
wikipedia( not always the most reliable source i know, but still decent) also states that 4 may be done at higher level:http://en.wikipedia.org/wiki/International_Baccalaureate