Its possible for a battery to go bad in 4 months time. I wish I would get 4 months warning when my battery goes bad. It could go bad overnight.

To ease your mind try this, drive the car or get the battery fully charged how ever you do it. When you park it at night, disconnect one battery terminal. The next day, connect the battery cable back up and try to start it. If possible, leave it disconnected for two days and see what happens.

There will be a certain amount of draw on the battery which is normal to keep the electronics working.

Sounds like a defective battery, but also to confirm you need a simple amp meter to see what draw you have while the car is shut off. I would be glad to check mine and we can compare.

Also if you take your battery to have checked, which is a very good idea, be sure it is fully charged or they won't be able to give you a solid answer.

James