Costco's recent earnings report has me considering an additional investment.Costco Wholesale (COST 0.13%) recently reported quarterly results. While investors shouldn't get too caught up in short-term results, they are important barometers of a company's progress.After reviewing Costco's sales and earnings, it reaffirms my belief in the company's concept and long-term future growth potential. That's why I'm considering adding a $1,000 investment in the stock.Granted, it will only buy one share at the curren ...