Do a little more testing to narrow it down. Its hard to fix a issue until you understand just what it is.
Take a 5 second exposure with the lens cap on. (Use AI Servo) This will let you see if any pixels are stuck "ON", but seeing the ones that are off is more difficult.
Set the aperture to f/22, but the lens in manual focus and set it to mfd, and take a shot of a evenly lit portion of the sky or white wall. Dirt and dust blobs of verying sensities will show up. A block of pixels that are stuck off are obvious. Usually, most dust will merely blow away with use of a rocket blower while the camera is in the manual clean mode. If that doesn't work, Canon will clean it for you, but it might not be covered under warranty, so ask. They are not always consistent about this, if you just received it dirty its one thing, but owning it longer might be treated differently.