It sounds as though the thread may have been cut through when the shipping box
was opened by the store clerk. I have noticed this problem with items in all
kinds of shops, including the yarn shop where I work. It takes very little
pressure to cut through a box or tape, and if items are packed tightly, the
razor can score the items below the box seam.

I'm with you, Joyce. I buy only Gutermann thread--cotton and
polyester, spool and cone---and I have never come across this problem.
Because it is in increments tells me that it may have been cut while
someone was opening the box.