Let's see, I've been bit by a small baby ball python (she was about 250 grams), a smaller brb and a 6-7 ft yellow anaconda. All of which, put together, hurt less than when I get scratched by one of my cats...we make it sound like its nothing because it really is nothing lol. This doesn't mean go sticking your hand in to find out, as you own a ball, its going to happen eventually. All I can say is even if yours doesn't like you touching its head, do it anyway, all mine I have done this with and now they act like a dog when you scratch the right spot, right behind the ear.

Ball Pythons
0.3 Normals (Coilette, Athena and Mary Jane)
1.0 Spider Morph (Zeus)
1.0 Mojave (Prometheus)
1.0 Pastel (De Sol)

Boas
0.1 Brazilian Rainbow Boa (Stella)
0.1 Hog Island BCI (Kiyoko)
0.1 Dumerils Boa (Gloria)
0.1 Yellow Anaconda (Serenity)