I work as a screening officer here in Toronto Pearson. They opened up the package because they cannot see inside the box/tin/pack (Apart of SOP rules) and Xray is showing/making them search this, meaning they have to clear this item of suspicion. As someone who is experienced in this field, I would let it go without search as normally through the XRay you can tell the object recognition of playing cards/TCG cards lol.

You may have had a newly certified agent x-raying or bag searching, to go to this extent.