Anyone have a problem with I phone 4 and checkout

[Danab]

Afternoon! I had a customer call me that had tried to checkout on her I phone 4 last night and when she clicked on the proceed to checkout button, nothing happened. She said she tried again today and the same thing happened. Luckily she called in and I took her order so I did not lose the sale. I do not have an Iphone to test this problem out on so I thought I would ask if anyone else has had any issues? I am using the one page checkout.

Thank you!
Dana