Root meowing?

I have a question about our oldest cat Root. When he was younger he would go through times where he would meow really loud every once and a while, we set an appointment to go to the vet, and he said nothing was wrong. After that, which was when he was about 2, he stopped for a long time. Now he has started again. He doesn't do it everyday, only sometimes. When we go to check on him, we usually find him just laying down. He is 9 years old now, and I was wondering if I should be worried about this. He doesn't ever seem to be in pain, and he only does it every couple days, so is this just nothing? Anyone else have a cat who does this? Thanks in advance for any advice.

Manda

Also I would like to say that bringing Root to the vet is not easy, so if we can find a way to not go to the vet it is a lot better. He hates the car, by the time we get to the vet he is panting from crying so hard. We are afraid of him getting to worked up over it since he is an older cat. So if there is a way to avoid the vet, it would be great. Thanks again for any advice given.

Manda

I wouldn't worry about it.
Every cat I've owned has done it off and on, sometimes I think they just like to hear their own voice.