this is where you just keep your mouth shut.
I have not looked at the limitations to charge a person with any of the several crimes that could be considered but 1 year is a very common limitation is crimes of a lesser degree.
Regardless, even if you could still be charged, a credit card receipt itself is not enough evidence to prosecute a person. There would have to be some support that a crime actually took place.
I would simply relax and do not speak to anybody about this as they could be potential witnesses if you could be charged. If the police want to question you, hire an attorney to go with you so you do not implicate yourself where they have no proof of a crime.