1986 Topps Complete Set Missing Cards

[Cmvorce]

Years ago I bought a factory sealed 1986 Topps complete set, which I just opened and put into a binder. Going through the set I discovered that it was missing 11 cards, mostly commons:

38 Glenn Hoffman
127 Jack Howell
330 Rick Sutcliffe
348 Cliff Johnson
372 Ben Oglivie
383 Chris Brown
581 Bruce Hurst
603 Bill Laskey
647 Mel Hall
659 Checklist 529-600
734 Marty Barrett

This set was 100% still factory sealed until a few hours ago. Were missing cards a known problem with factory sealed sets from Topps in the 80s? I still have to go through 87-89 and I’m wondering if I should expect the same. Thanks all!