Batteries do age, even more so without a charge. Usually they are ok for about a month or so. When you get to 2-3 months they should really go on a battery tender.
There is math that can be done to calculate out how long the battery can sit uncharged for before it drains. I just don't feel like looking up the specs to calculate it out, but the point is there is a finite time period.
I echo what was said to look at the battery manufacture date. 1yr or older shouldn't be used period.
With that said, automotive repair would have been considered essential so the sale of batteries in general still could have continued. I would think the issue would be supply of batteries would be low, vs the issue of too many sitting on the shelf for 2-3 months.