What RPM was the engine turning when you measured that?
Also, what was the state of the battery? Had it been on a battery tender before you started the engine? If not, then I think what you observed is normal.
What voltage do you observe after the engine is fully warmed up and the battery topped off and the engine turning say about 2,500+ RPM?
also check the battery volts with engine not running . It could be the scaling of your meter is low . From not running to running you should have several volts of increase . If you watch the meter while cranking over the engine it should drop several volts while battery is under load .
My first thought is that it is not good. A better test is the trend. Is the voltage increasing or decreasing? If it is dropping you are on your way to a dead battery and more investigation is required.