They wont ask to see a print out will they - just the reference number is required is that right?
well we had a different experience dave was asked for a print out as someone of the same name had been refused entry to the usa we were at the desk ages and lucky i had printed it out
Just found this:
Do travelers need to bring a paper printout of their travel authorization to the airport?
No. DHS will be able to communicate a travelerís ESTA status to the carriers. However, DHS recommends that travelers print out the travel authorization application response in order to maintain a record of their traveler authorization application number and to have confirmation of their ESTA status.
Fingers crossed we will be ok
i print everything out i must admit and as i have said it was a good job we had
dont worry you will soon be there and enjoying your holiday