To my knowledege, everytime you request a credit line increase to AMEX, you get your credit report (hard inquiry) pulled by AMEX. (right?)

I had been doing a credit line increase over the past year pretty often and am now worried. When exactly do they pull a hard credit inqury?

I ask because when you click that link on americanexpress.com to request a credit line increase, it sometimes just tells you that you are pre-approved for this much increase, (dollar amount). Do they just pull an inqury WHEN you click this link to get to that page where it says how much you can increase the credit line by? Or do they pull an inquiry when you accept that offer? Or do they even actually pull an inquiry?

I'm so confused.. help!