Memory warning and crash in iphone using assetBundle

Hi.

I'm using assetBundle to download all the required textures in my DLC. Once the user buys the content the download starts, about 60 textures in various sizes. The download works flawessly in Unity enviroment, but in the device receives a memory warnign and then crashes, so:

• I'm using an different AssetBundle for each texture, each assetBundle is being downloaded in sequence, one at the time, would it be better if I used a single AssetBundle for all the textures ( just about 2.6 MB in total).
• After downloading each texture I instantly assign it to a material...this impacts my avaliable memory ?
• What can I do to download all the content without memory warnings and crashes ?
• I'm supossed to somehow release or free my asset bundle ?

Thanks !

This is my chunk of code, being called for each assetBundle:

public IEnumerator LoadTexture(string packageName, string materialName) { staticDownloads++; int downloads= staticDownloads;

     WWW download = new WWW ("http://www.mywebsite.com/MYGAME_DLC/"+packageName);
     yield return download;
     AssetBundle assetBundle = download.assetBundle;
     Texture2D go= assetBundle.mainAsset as Texture2D;

     Material mat= Resources.Load(materialName) as Material;  
     mat.mainTexture= go;

     if (!go) Debug.Log("Couldn't load "+ packageName  );

}