The target is shopping at Windsor
While it can be flattering to know that people are talking or thinking about you, flattery probably wasn’t the goal here. After asking someone where they were, the original texter “accidentally” sent a confirmation message to the same recipient, informing some unknown part of their whereabouts.
The best part is that they didn’t elaborate. They simply replied with an “oops, wrong person,” and that was it. If your goal is to instill anxiety in a person who has a difficult enough time making it through the day, this is the way to do it. A “take him out” would also be a nice touch.