Battery or starter going out?

[Yarflana]

Situation: sometimes, and only about 1 of every 15 starts does it do this whether warm or cold, when I turn the key to start the engine, instead of starting right up, the engine turns over a few times and sounds like it is trying to get going enough to start, but always starts. It always ends up starting, however, so I have never had a situation where it tried to start and wouldn't.

Concerning maintenance and mileage, my car has 100K on it, just replaced the plugs with stock iridiums, battery is about 4 years old, oil is Kendall synthetic, regular maintenance always (oil change every 5,000 miles on 95% highway miles).

Could be battery on the brink since it is 4 years old.

In the morning when it is cold, even when it is 30 degrees, I don't ever remember this being a problem and always starts right up.

I have never had a car that needed a new starter, so I am not sure if that is going out, or if I really don't have a problem. I want to get any pointers you can think of and nail this down before I do have a problem and I don't want to go to the auto shop either, but I do have a good relationship with them and they would likely check my electrical system at no charge.

Let me know if you have other questions.

Thanks for your input as always,
Pat