Yeah you never see it in the movies, but there are plenty of EU examples. Leia later uses red, as does Saba (one of the members of Luke's Jedi Council).
Furthermore, and here is a bit of trivia for you
Way back even in Official Cannon history many Jedi used any color of crystal they could get their hands on. Though the Sith still mostly used red crystals, due to being cut off from the crystal caves of the frozen planet of Ilum and having to synthesize their own crystals; and red crystals are the easiest to make in this way. It was only later that they started saying it was for this, this and this reason when it was just a act of necessity.
Revan as a Jedi, used a purple saber, then when he turned to the dark side his purple saber remained and he ended with duel wielding a red and purple lightsaber. Then when he was turned once again this time to the light, he kept both his lightsabers. Thus as a Jedi using both a purple and red.
(Thank my husband for his love of Revan for this tidbit he has stuffed into my my brain along with all the other useless Star Wars Trivia)
Samuel Jackson (who is more used to playing the bad guy) better know as Jedi Master Mace Windu wanted a red lightsaber, but was told no because it was a Sith only color.
They used the Green and Blue vs the Red in the movies in order for movie goers to tell if the character was a good guy or bad guy.
