Get Asset Preview (3.5)

So we are working on finishing up our editors for our game and haven't upgraded to unity 4. I know there is a function EditorUtility.GetAssetPreview(). Here is my problem:

Below is the code I am trying to reference. Essentially, I am reading in a list of game objects from various file paths. I am loading each object in, and trying to render a preview texture of it (for a custom editor). However, I am getting very weird, inconsistent results. Essentially, I have ~80 prefabs in the paths I am trying to load. Of those 80, either 7 or 13 textures are actually created. I can't find anything in their documentation limiting the amount of textures that can be created, I am only loading and performing the render ONCE. If I close the window and reopen, triggering the reload, I get a different set of prefabs.

Essentially on first load I get 7 textures. On second load I get 13. And it switches back and forth if I continue this. I have debugged the code to ensure I am getting valid game objects, but it isn't being rendered. All the prefabs are more or less exactly the same (minus some script values) so models and such shouldn't be the issue (as they are the 'same'). It's like the GetAssetPreview doesn't have the time or resources to create the textures but that doesn't make sense as it's not asynchronous.

Any help or insight you can provide, I would appreciate. Thank you for your time.

     /// <summary>
     /// Reads the in all objects from the paths.
     /// </summary>
     /// <param name='paths'>
     /// The paths to read objects from.
     /// </param>
     void ReadInAllObjects(string[] paths)
     {
         // just testing...
         int totalObj = 0;
         int totalLoaded = 0;
         int haveImages = 0;
         
         // iterate over all paths desired to be loaded
         foreach(string path in paths)
         {
             // read in all files from the given path
             string[] allFilesInPath = Directory.GetFiles(path, "*.prefab");
             totalObj += allFilesInPath.Length;
             
             foreach(string filePath in allFilesInPath)
             {                
                 //string newpath = filePath.Replace(@"\", @"/"); // not needed, but makes file path cleaner
                 GameObject obj = (GameObject)AssetDatabase.LoadAssetAtPath(newpath, typeof(GameObject));
                 if(obj is GameObject)
                 {
                     ++totalLoaded;
                     Texture2D texture = EditorUtility.GetAssetPreview(obj);
                     if(texture != null)
                     {
                         ++haveImages;
                         gameObjects.Add(new ObjectTexturePair(texture, obj));
                     }
                 }
             }
         }
         
         Debug.Log("Total obj: " + totalObj);
         Debug.Log("Total loaded: " + totalLoaded);
         Debug.Log("Have images: " + haveImages);
     } // eo ReadInAllObjects

 /// <summary>
 /// Object texture pair used to link a texture and an object so 
 /// it's easier to manage and not lose or duplicate information elsewhere.
 /// </summary>
 public class ObjectTexturePair
 {
     public Texture2D texture;
     public GameObject gameObject;
     
     public ObjectTexturePair(Texture2D texture, GameObject gameObject)
     {
         this.texture = texture;
         this.gameObject = gameObject;
     }
 } // End ObjectTexturePair