Clunk heard when letting on/off gas?

[solarflare]

Just curious, I have an 08' H2, and just recently I noticed that I have a clunk when I take the foot off or put it on the gas pedal.....It's a hard noise to describe, but it's almost like the driveshaft making the noise.....It doesn't do it all the time, but it's annoying.....
It's only started doing this since about a week ago. I have approx 6800 miles on her now....any thoughts would be great!