well, of the possible parents you listed, 2 are tets and 1 is a dip...(Centerpiece and Rocket Cty are tet, route 66 a dip) (And, to be honest, your seedling does look like a CPxRC...can see both flowers in yours)
My guess would have to be that it was the two tets you had actually paired up, so your baby should be a tetraploid.
