Getting ReadPixels error, but not calling ReadPixels, project runs fine.

I'm working on an iOS app for iPads using Vuforia and NGUI and recently upgraded to a Unity Pro license. Running the project in the editor gives me the following error, apparently being called every frame:

ReadPixels was called to read pixels from system frame buffer, while not inside drawing frame. UnityEngine.Texture2D:INTERNAL_CALL_ReadPixels(Texture2D, Rect&, Int32, Int32, Boolean)

I am not calling ReadPixels anywhere, but it does get called in WebCamImpl.cs in GetPixels32AndBufferFrame(int frameIndex), that's where the error is coming from, and I'm pretty sure that method is being called by Vuforia. I've noticed another post here, where someone describes a similar problem starting after upgrading to the Pro license, and using Vuforia. This seem like a bug, and I wanted to see if anyone else is experiencing a similar problem. As I said my project runs fine, fortunately, but I want to get rid of this error. I've looked on the Vuforia forums with no luck and am going to post there too. I'm sure others are dealing with this as well. Thanks.