Actually I think you have a surprisingly balanced sample:
QUOTE(dcherry @ Oct 20 2011, 20:50)

500 manbearpig tails
12 phase (5 were fox/owl)
122 gossamer
366 cotton
30/10/1 → 30/41 chance for Cotton, 10/41 chance for Gossamer, 1/41 chance for Phase
500*30/41 = ~365.85 = 366 Cotton
500*10/41 = ~121.95 = 122 Gossamer
500*1/41 = ~12.19 = 12 Phase
My inner OCD person is very happy at this.