Hmmm, I'm glad this Lindsay zipper pull issue was brought up. I recently got my teal Lindsay about 2 months ago and have used it twice, but I decided to lubricate the main compartment zippers since they weren't running as smoothly.
As a result of pulling directly on the leather zipper pulls (the stitched part) back and forth like about 20 times, one of the thread came loose. I thought about sending Lindsay back to Coach for repair, but decided against it (separation anxiety, lol), so I ended up fixing the problem myself by sewing it back together with a similar color reinforcement thread.
Now the problem is gone and from then on, I try to pull on the metal rings of the zippers or lower part of the zipper pulls to prevent any future threads from coming undone.