Why would fed ex cut open my package that  I Sent ? ?

I have a small PayPal business account I use to ship workout supplements  in . A lot of my stuff is overnighted for the past 3 years . My lady said when she went to pick up her package at the fed ex store they had tore the package open and the lady told her at the fed ex store that was how she got the package from the driver and she did not see what was inside and asked my lady if she still wanted the package which my customer still took . I'm just wondering why they would do this without telling me . There was no drugs in it just diet pills .