Noticed a small bug at The Daily Deal with Zachary's Boots. Even though I don't own them, the exclamation mark doesn't appear.
I replicated this behavior below: Spoiler Blue destruction on the active party roster member says I have 1. Selecting the next character hides the item so I have 0 displayed.
The item count popup is bugged and doesn't count items equipped by inactive chars. This becomes very obvious when in co-op, since you'll usually have 2 fully equipped inactive chars then.
For the record I do own them. They were equipped on an inactive multiplayer char as Kalin stated and DupleX replicated.