1982 String Box

I just opened a String Company box that is completely 1982's. I'm a hand-sorter so I started weighing them. After 6 rolls I am at about 39% copper. All the pennies are very circulated. I do about 10 boxes a month mostly from a number of different TD Banks (always String boxes). However, I do hit this small Credit Union sometimes and this is where I got this box (they always have String boxes too). The funny thing about the box was that it was taped shut with masking tape like it had been opened from it's original sealing. However, the rolls were factory sealed like they normally come and not customer or bank rolled. Any explanation for this? Not really sure how String operates.