Depends on your Go's Condition...
The Go's I have played with have Glow the Light bar when unlocked, however, there is always an App running, the Phone App (SIM Card if inserted and activated) will blink it, the Just Type bar will also blink it depending on what you are doing, if you have any notifications (Dash Weather/Weather Widget/Battery Widget/Toggle4GWidget) they will also blink the light on, If you have a message/email/some other notification that has been accepted but not removed, this will also keep the light on.
Open up a webOS app, then minimize it if the light goes away then it is a default app that is lighting it up.
Although the Go's I have played with also have ACL and have a very modified webOS YMMV from mine.
But this is might be normal depending on your current situation.