Entered US on visa waiver program but stamped in for 6 months

[captikus78]

Hi there - I entered the US via a cruise to Hawaii a few weeks ago. Before boarding the ship I applied for an ESTA, which was approved. Then just before docking in Hawaii I was given a paper copy of the ESTA form to fill out again which I took to the immigration officers who boarded the ship when we were docked in Maui. They took the form and stamped me into the US for 6 months - which was a surprise as my understanding was that entering on the visa waiver program only entitles you to a 3 month stay. Does anyone have any idea why they might have stamped me in for 6 months? I would love to stay for the full 6 months but don't want to get into trouble if I go with what the stamp says but am in violation of the terms of the visa waiver program - does anyone have any experience of this or any ideas about whether I can stay for 6 months?
Thanks in advance
Captikus

[newacct]

And what was your class of admission, WT or B2?

What does it say on your electronic I-94?

[captikus78]

Hi - thanks a lot for getting back to me - the admission stamp says WT/WB. There appears to be no record of me on the electronic I-94 system. I was surprised when dealing with the immigration officers on the cruise ship that they didn't have computers, they just read the forms and stamped the passport - so I'm not sure if that explains why there's no record of me on the I-94 website?
Any ideas?

[Japm]

That happened to me when I entered in Newark back in 2008 (WT). I have no idea why