Was on iHerb's facebook page and noticed in a facebook message they stated
To jump start iHerb's new Loyalty Credit program, a loyalty credit has already been added to your account! To use it, simply shop as you normally would and you will see the credit applied to your order once you have logged in.
I placed a dummy order and i saw a $36.03 credit applied to my account. I also haven't made an iHerb order since 28/3/2014. The loyalty credit applied to my account is exactly equal to 5% of all my orders combined prior to 28/3/2014.
You will see the discount applied when you place an order.