error Shipping "Estimator

My /logs are showing this repeating error:
PHP Warning: Illegal offset type in xxxxxxxxl/includes/modules/shipping_estimator.php on line 132

The code referenced (the last line is 132):

// set the cost to be able to calculate free shipping
   $order->info = array('total' => $_SESSION['cart']->show_total(), // TAX ????
                        'currency' => $currency,
                        'currency_value'=> $currencies->currencies[$currency]['value']);

Don't know if its relevant - my default currency is CAN$, and I also enable US$. My site www meafordwool dot com is in Canada and my server is in US. I have Canada Post mod installed and working. I haven't had any reports of problems from front end.