Here is the full warning.
On Load:
SendMessage cannot be called during Awake, CheckConsistency, or OnValidate
UnityEngine.MeshFilter:set_sharedMesh(Mesh)
tk2dSprite:OnValidate() (at Assets/TK2DROOT/tk2d/Code/Sprites/tk2dSprite.cs:118)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)
On Play:
SendMessage cannot be called during Awake, CheckConsistency, or OnValidate
UnityEngine.MeshFilter:set_sharedMesh(Mesh)
tk2dSprite:OnValidate() (at Assets/TK2DROOT/tk2d/Code/Sprites/tk2dSprite.cs:118)