The first issue is an extra notice in some cases. This all works 'fine' with PHP 5.1, however with PHP 5.2 the [following] notice was generated for this code.
The cause? Well, the magic function __get only returns the variables in read mode so they cannot be written to. In Derick's situation, there was a foreach that was trying to use the values in a read/write mode. As a result, the error was tossed. He does provide a workaround, though, involving casting the information into an array.