Kathleen - I was going to say the same thing as Gregorio. Depending on what your fees and costs are, a difference between a 5% rate and a 6.18% APR may or may not be that unusual. As Gregorio mentioned, if this is an FHA loan a 1% or more discrepancy is not all that unusual if you are financing your UFMIP (which most borrowers do).
However, if this were an FHA loan, I would question the 5% interest rate more than I would the spread between the rate and the APR. Right now, FHA rates are lower than that even with a credit score adjustment. I just locked one of my FHA buyers in at 4.375% and that was with a rebate (YSP) that was more than enough to cover their lender fees.
However, if this were a conventional loan with an LTV higher than 80%, then a 5% rate with some adjustments wouldn't be out of the ballpark. As someone else mentioned, without more info (which I am not requesting), its hard for anyone here on Trulia to answer your question based on the limited info you've provided.