I would not worry about it, over time all batteries fail, generally gradually.
The time it remains charged sufficient for use, depends on your usage, together with the strength of the battery.
When it becomes clear charged time duration is low, replace the battery. Check out ebay and amazon for replacement batteries.
I purchase those with a higher wattage than the original.
Also do *NOT* go for the ones with lots of cells e.g. generally 6 is the same as the original. Some are offered with 12, which I feel is adding to the possibility of failure.
If you have the original battery, there will be a model number or numbers on it, that will help you to identify an oem replacement. Use the number(s) together with the make and model number of your laptop.
Here in the UK, oem batteries can be found for around £20.
If the laptop is heavily used and the battery fails after a year, I feel that is acceptable. I recently purchased one with a 3 year guarantee.
Please advise back what you decide.
Good Luck - Keep us posted.