No, you should use your credit card protection if that is the case.
If you pay through PayPal, you only have 45 days to be reimbursed; hence, if you don't receive your items within a month, which is a more than reasonable amount of time, protect yourself; Priority Shipping through the USPS is 2-3 days, and it has always arrived to my customers in the United States withing 2-3 days for every one of my customers.
When you sell online, you must ship. Lost shipments are the Sellers responsibility, just as purchasing insurance is for the Sellers protection, not the buyers. Delivery Confirmation is automatically included through Fed Ex and UPS, and if you print your postage online it's free through the USPS as well. Even if you don't print your postage through online for the USPS, it's only .50 cents; again, these measures are for the sellers benefit, not the buyers. When you accept PayPal or traditional credit card, it's all the terms of service, so there is not really an excuse on that argument.