In the absence of significant trauma, it would be unusual for any nasal cartilage grafts to come loose. Most nasal cartilage grafts are sewn in place. I typically use PDS suture...which is absorbable. However, it takes about 3-4 months for the suture to absorb...just long enough for your body to grow scar tissue that will keep the graft in place.
Nasal cartilage graft
It sound like you are pleased with the result currently. If the graft becomes a problem it can always be removed, but it sounds like it's doing fine.
Nasal Tip Grafts
Nasal cartilage graft are placed for a purpose, most often cosmetic but frequently to augment structural support. Sutures hold them in place until the soft tissues (normal scarring) is sufficient. They can be removed surgically but the indications are rare. If the correction is good now, it will be good for many many decades, even though the cartilage can warp, on occasion.
You are confused. Sutured grafts are more secure and less apt to be misaligned then onlay/Peck grafts. That's why most surgeons like to suture grafts.
Best of luck!
Nasal tip grafts
Nasal tip grafts typically sutured to the underlying nasal cartilage to keep them in place until scar tissues are formed. Permanent sutures are also used. Essentially, once healing is complete, graft should stay were they are placed but forces of scar contracture can displace them even when sutured in place. Nature sometimes has its own rules. Best
Don't know what peck grafts are, but you should remember that grafts integrate and are non-mobile after one month; sutures are not present when we go back for a revision rhinoplasty and the grafts are secure.