If it were me, I would replace the battery. A battery can test fine one day, and leave you stranded the next. I learned my lesson after it happened to me.
Batteries start losing their reliablity after they become three years old. After that, anything can happen with the battery. Look at it like this, would you rather have the battery fail at the most inopertune moment, and pay for a tow AND a battery? Or replace the battery now and avoid that inconvenience? Replacing the battery now is pretty cheap insurance against that happening in my opinion.
Tester