I know there are a few threads already regarding this, so I apologize for a little redundancy!
I took my bike (still relatively new - a Giant OCR2) in for a tune up at the start of season. The bike had about 300 miles on it when I purchased it used last summer. This is my first road bike, and I've put around 1100 miles on it this summer. I've been lubing the chain / shifters every few hundred miles, and everything is still rock solid.
However, in the past hundred miles or so, I've noticed a "clank" noise every pedal. It feels like it's coming from the left side, and from the crank. I tried tightening the bolts that hold the pedal arms on, but they all seemed fine. I even took them out to lube the threads a little bit. However, I noticed a slight "play" in the axial direction. If I grab onto each pedal, I can move the assembly a slight amount side to side (axial to the crank down the shaft). Could this be what's causing it? Is this a concern that I should check out right away, or something that can wait for a tune-up come next season (with only a month or so left of riding here) ?