PO300 code/PO302 code

About seven months ago I had the same code come up (random misfire and #2 cyldr.) After about another seven months of sporadic diagnosing it was found to be all four fuel injectors (body casings were all cracked) all four were replaced with OEM sensor. The code went away for at least seven months, now when the check engine light came on it showed the same above mentioned code on my scanner. I talked to several mechanic friends I know and they said it is probably a "fathom code or hidden code" just cancel it which I did and it has not come back for about forty five miles of driving. Is this the case, because I am not familiar with a hidden code? Also will a misfire produce a check engine light immediately within the first loop of driving?