In order to display the homozygous form of Albino, the off spring have to get one copy of the albino gene from EACH parent. If you breed two hets together and you produce an albino - you've just proven BOTH of your hets to be 100% het albino, because if either one was NOT a het, you would not produce an albino.
Keep in mind though, if you don't produce an albino in your first breeding, that does not DIS-prove that either of them are het. You'd have to breed them a few more times to make sure that you weren't just missing the odds.
You might find this helpful to understanding recessive genetics a little better.
http://www.ballpython.ca/what_get/recessive.html
Here's where you can also see dominant and co-dominant examples as well.
http://www.ballpython.ca/genetics.html