This is the issue!  Spot on!

The same item was in the sold section + the unsold at the same time.

Then the sold item gets relisted  because it is in the unsold section, when it is really sold.

The eBay computor corrects the eBay  malfuntion after, say, 5 min and I am...........

But in the sold section it does tell me that the item has been relisted and that is why I know that something is amiss with the listing.