I can see a few specks in my 70-200mm f/4 L. Hadn't noticed them before today, and they've never given me any problems. I'd suggest doing two things...
1) Take some pictures with the lens. They should be wonderful. If it's not giving good pictures (assuming proper technique is used), then maybe there's a problem.
2) Swing by the camera shop, see if they have another lens that doesn't look the same way. Maybe you could exchange it for peace of mind.
It probably shouldn't affect image quality. I bought a 35mm f/2 on ebay that went for a song because the owner complained about a piece of dust inside the lens. He posted photos showing how the dust inside the lens appeared in a photo of blue sky. When I got the lens, sure enough, there's a larger dust speck inside it. However, it didn't show up in any of my photos.
The seller simply had dust on his sensor.