Heh. Qt was released in 1995 and the The Cathedral and the Bazaar was released in 1997 with the OSI being formed in 1998. This means Qt pre-dates the term 'open source' by approximately 3 years!
Well, to be fair, Qt was aware of the free software movement from near the beginning. Richard Stallman tried to convince them to liberate their code, and resulted in pushing for a free software replacement. The existence of that free software replacement forced Qt's hand and they released their code under the LGPL. The OSI, Eric S. Raymond and the other "open source" people were not involved AFAIK.