When a package through USPS says pending acceptance it could be that the package just has not been fully processed yet.
Or the package did not get an additional scan before it was sent off to a sorting facility.
I have had packages being shipped through USPS that were stuck on pending acceptance for a few days or until the package actually reached me.
It does not mean that your package was not accepted as sometimes USPS employees don't always scan packages like they are supposed to.
Regardless your package is likely still in transit even though the tracking is stuck on pending acceptance.
I would not worry until it's been 5 to 7 days and you haven't received your package.
I've also had USPS packages delivered to my post office and I got the package and yet it still says package acceptance pending.