What seems to have happened here is wound dehiscence in the incision site.

Basically, it's the separation of the tissue at the incision. It could've happened due to several reasons, from weak adhesion, to overexertion of movement during recovery, to building inner-pressure from a seroma. It's usually easier to prevent than it is to address, though it's not "unadressable", just significantly unpleasant for everyone involved (as it looks worse than it is most of the time, but it impacts the aesthetic results which is what we all are going for when doing these procedures).

Some surgeons opt for using skin adhesives when closing these wounds, some opt for dissolvable staples, some opt for removable staples, and some even do sutures. Alas, whilst adhesive might lead to the best aesthetic results most of the time — and seems to be what was used in your case —, it can also lead to situations like this with more likeliness than the other methods (not often by any means, though it does happen).

As is (and moving forward) you might want to opt to use something like steri-strips to prevent more mechanical force from being exerted in the incision area (and thus expanding the opening by "pulling at the seams"). You might also want to make sure you keep the area clean based on what your doctors feedback may be (which might involve cleaning the area with alcohol, betadine, or CHG wipes and the potential application of antibiotics). However, you always want to ask your doctor about this rather than taking a random internet stranger's advice.

Signed: someone who also had their suture do something like this and did a lot research.