Spreader grafts are typically secured in your nose with sutures. BUT, this depends on how they were placed. In an external approach rhinoplasty - where you have a small cut on your columella; spreader grafts are always sewn in place. In an endonasal approach rhinoplasty - where everything is done inside your nose with no visible cuts; spreader grafts are placed into a secured/tight mucosa (nose lining) pocket. While they aren't sewn into place, they are quite secure in this technique. It would be very rare for them to move or become dislodged with either technique.
If something has happened that is making you concerned that they've moved or become dislodged, I would strongly encourage you to see your nasal surgeon and be thoroughly evaluated.