Assuming the spring is torsional (one or two springs coiled at the head of the garage door), you'll find out if it's about to give in another couple months when it get's really cold outside.
It might just need adjusting, but it it's vibrating and the spring gets really cold... snap.
I've had 2 replaced on 2 separate houses in my 13 years of home ownership. Par for the course.
Like said above, I'd just make sure none of the linkages / chain are dragging and the door opens and closes smoothly, without anything catching. If it's a spring adjustment and it's a torsional spring, I'd recommend just using a local garage door company to service, one mistake and it could break you. Nothing worth hurting yourself over if you've never serviced. Be there when the guy services it (whether it's a new one or adjustment of an existing one) and you can see what it takes.