I'm not sure the secret would be out, VisionGirl. Things like that happen so fast that witnesses rarely know what happen. (That's why there are so many disagreements about the shooting of John F. Kennedy.)
Who's to say it doesn't richochet off his arm where it's bent off his side leaving a small window for it to go thru? In that case though, Clark could pat himself down frantically going - "I'm hit! No, I'm not hit! How'm I not hit?" cue Lois groaning and falling forward against his back - "Oh... oh boy."