I have bought 1 ISA brown 4 weeks ago as a 1 week old sexed pullet from a local market in Bangkok but I can't be sure if it is a correct sex link, or just a mixed breed. The color is correct for a pullet if its a sex link, the comb is still small and yellow, but I am worried about the tail feathers. "She" has very little and short tail feathers. She is about 5 weeks old in bellow pictures. Should I be worried?