My numbers assume that you started paying on a 30-year $400k loan in November 2013, your current balance is about $395k, and you would lose $5k equity to refinance and start paying on another 30-year $400k loan in September 2014, with an interest rate of 4.375 instead of 4.875.
With the better interest rate, you would save $119.69 on your monthly payment. The savings in cash would break even with the loss of equity in 20 months. Your total savings through 30 years would be $24,000, which could actually be a lot more if you invest the savings.
Note that you can shop around. Look up mortgage brokers for better rates and lower closing costs.