Hi,
Do you know the sexes for definite on the 4 normals? Because yeah that does sound a good deal for 4 females but for four males not so much unless you only want them as pets.
I wouldn't read anything into the yellow belly mother unless you can see the offspring are actually yellow bellies - it's the same idea as "pastel sibling" really. In an ideal world it would mean they took extra care to find the best looking mate to produce good looking offspring but sadly all to often it means as much as "my aunt had a canary once till the milkman left the window open" during a discussion of quantum mechanics.
It might be worth asking him for belly pics or something unless you don't mind getting 4 male normals.
I know you said two of them were really light and appealed to you so it really comes down to what your plans for the animals are.
dr del