Unless you know you bought a specially grafted plant, blueberries grow on their own roots, which means the sucker problem doesn't happen. A sucker is a shoot that grows from below the graft point on a plant which has been grafted to a different rootstock; the sucker is a shoot from that rootstock, and therefore not desirable because it takes over from the grafted plant on top, above the graft, which you do want. In this case, the new shoots you're seeing are just fresh blueberry growth.
UPDATED ANSWER: in response to your comment, have a look at where its coming from, that shoot - its probably arising from the roots, because the roots have spread and grown and it's simply throwing up new growth because it can now it's got a larger pot.