There definitely was a bug in the past that made purple nymphs twice as likely as any other nymph, but even when that is factored in, I also have more purples than any other element. (12 purple, 1 death, 4 gravity, 3 earth, 3 life, 5 fire, 2 water, 3 light, 2 air, 2 time, 2 darkness, 2 aether) It's probably just pure chance in both our cases.