I don't know if it's common but I have noticed it before.
However, do bear in mind that at near distances, as in your case at 1m, your depth of field is shallow, hence errors in the AF become more prominent. At further distances say 5m, the depth of field is deeper, hence errors in the AF is less prominent. I'm quite sure your less also back focuses at further distances but the back focus is less obvious due to depth of field.
Back focusing by 0.5cm sounds quite significant to me but Canon does allow tolerances in AF errors. I'm not sure if this is within the tolerance.