I worked in a pawnshop located across the street from a large public housing complex, but also in an upscale shopping center, 6 days a week for nine years. I was the only employee, with no other help, for those nine years. It took quite a toll on me.
Trust me here- John Steinbeck and Stephen King could not invent a story I haven't heard!
EVERY strata of society occasionally use a pawnshop, including doctors, lawyers, accountants, bankers, and preachers. The fact is, people use a pawn shop for ANY reason you can possibly think of that people need money. Unexpected repairs, emergency travel, normal bills, laid off, illness, drug habits, etc, etc.....
My policy was that if an item was still unsold, the original pawner, or family thereof, could redeem it for whatever was owed on it, no matter how late they were.
I tend to believe the story here.....pawnbrokers rarely chase a good deal they give by mistake. Better to just let it roll, satisfied that the buyer will spread the word about what good buys can be had at THAT shop.
There is a SIMPLE fix here- get her phone number, or agree to meet her at the shop at an appointed time. She may have been sick, unemployed, or out of town when it came due. Or, she may have loaned it to a brother or kid to pawn when they needed money, and not realized they were defaulting.
It could not hurt to talk to her, and see what "feel" you get from the story. I am sure I got conned many a time, but I always figured it was better to err on the side of kindness rather than being hard.
If you decide to let her have it, let the shop book it back in, with the understanding that you get to witness the transaction of her redeeming or renewing it.