It is hard to say what you should do without knowing the rest of your financial situation.
But, 4.87% is pretty high. To me, it depends on what the $150k is invested in and what it is earning and whether your are working or retired, if you are working how stable your job is, your personal risk appetite, etc.
If your risk appetite or investment return is low and $28k would be a sufficient emergency fund for you then pay off might make sense. Otherwise you could refi into a 15 year mortgage at probably less than 3% and as long as your $150k of investments earn more than 3% over the next 15 years you would come out ahead, but recognize that if your investments earn less than 3% then you will come out behind (assumes that interest income is taxable and interest paid is tax deductible - YMMV).
As for me, I am accepting of risk and believe my investments will earn more than my 3.375% mortgage interest rate in the long run so I refi'd earlier this year and sleep well at night knowing that if I wanted to or needed to I could pay off my mortgage anytime I wish to and that my mortgage is only about 10% of my nestegg.