I am an attorney and I know a lot about the subject of shoplifting. I am not licensed in Pennsylvania, so I will speak to general principles. Do not take this as creating an attorney-client relationship. Here is my opinion.

Are you at risk for what has happened so far? Theoretically yes, but as a practical matter, the risk is very low. From your description, your friend apparently got away with it. The vast majority of apprehensions are done on the spot. Even if the store figured out your friend stole something and “made” your vehicle from surveillance video or some other means, the only evidence against you is that you provided transportation to this person. In order to be liable as an accomplice, there has to be some evidence that you knew your friend was stealing and that you assisted in some way. There is evidence of assistance - the transportation - but it sounds like there is no evidence that you knew what she was planning to do.

The only possible source for evidence against you sounds like your friend. In other words, if she got caught after the fact (sounds unlikely) and then implicated you by her statements for some reason (even more unlikely) then that could be a path for trouble for you. It sounds pretty remote, though.

However, going forward, the circumstances are different. You have reason to think she is a thief. If you provide transportation under similar circumstances and she steals again, you probably are guilty as an accomplice. It might still be difficult to prove next time if you stay in the car again, but with each repeated theft your risk would increase.

I would also recommend staying away from that store for quite awhile, perhaps a year or longer. They might have an eye out for you and that could lead to unpleasant experiences.

As you probably know, your friend needs to get help with this. If she keeps on shoplifting the odds of her getting caught approach certainty. It can cause a lot of grief for a stupid crime.