Costal cartilage is an ideal autologous graft. However it has its disadvantages. One of which is "Warping". Warping may happen because costal cartilage is a viable tissue and it also has "Internal stress" within it.
Warping may occur in 3-5% of cases. Simple warping can be usually corrected endonasally. But In case of severe warping like this photograph, we should take out the graft and then re-insert.