Ocelot

Sometimes, when im going pretty slow, then go into wot in 3rd, it sounds like i ran over a twig or something when i start to feel the turbo kick in. Its wierd, i dont feel anything different, and when i try to replicate the sound over again, i cant do it, it only comes up at random spots when i'm not expecting it, but wot in 3rd seems to be when its making the sound. For all I know I could have just run over a few twigs, lol, but i was just wondering if theres anything that would sound like that which would be a problem?