No, I am not falling for the Gambler's Fallacy.With such small numbers you are actually falling for what is called "Gambler's Fallacy"
Law of small numbers may result in Gambler's Fallacy. For instance, when flipping a coin and get 6 heads in a row, individuals will start putting too much probability in the next flip being a tails. And this is a reasoning based on just small amount of data in the sample.
What I am trying to say is that "All Chicks Hatched with single comb" on a single clutch of eggs is still within probabilty(however small it is) In order to get 50% p+/p+ and 50% P/p+ we need larger number of hatches.
I do not think the "next" coin flip (or chick) has a higher chance of having the other trait.
But by the time you get 6 heads in a row with the coin, I start thinking something is odd. And by the time you reach 10 heads in a row, I'm checking whether the coin has 2 heads, or whether someone has found a way to flip the coin so it always lands heads up instead of really being random.
With chicks, if someone gets a batch of 10 with one recessive trait, I think the most likely explanations are:
--parents are both pure for that trait
--those "parents" are not really the parents
--the person is mis-identifying the trait
So with a cockerel who clearly is not p/p for single comb (because we've now seen his picture), but "all" his chicks have single combs when their mother has single comb, I would want to know how many "all" the chicks are.
If it's 4 or less, then I think random chance is the most likely explanation.
If it's a few more than that, chance is still a reasonable explanation.
But if it's 10 or more, then I think the MOST likely explanation is that a different rooster sired some of the chicks, or that the person is mis-identifying the comb type. Random chance is not completely ruled out, but is not very likely to cause that.