The comb has some color but is small, but there is early wattle development. You are right to be suspicious but I think it is too early to sex this one accurately. Post back with new pictures in a couple of weeks if it isn't clear by then.
A cockerel this age would have a good sized comb and wattles. Sussex comb up early. There are slow developers, but nothing about this chick says cockerel yet.
I also think it's a bit too early to tell for sure yet. Update in a couple weeks It doesn't have a large comb though, which is always a promising sign!