It may be a basis to move to dismiss the indictment, especially if the prosecutor failed to take any steps to inquire if any grand jurors knew the defendant.
The identity of grand jurors are not generally shared with defendants. An application would need to be made to confirm that the grand juror was biased and voted to indict or participated in deliberations or "getting the defendant" as you have described it. It would be difficult to confirm as other members of the grand jury shouldn't be sharing information about the grand jury functions. If there is a grand juror speaking about the deliberations etc. it could undermine the integrity of any vote taken and may expose that grand juror to criminal liability. You should bring this to the attention of the defendant's attorney.