When I get clumps from Oakes, I have also received bonus quack grass in there as well, on more than one occasion. Insidious stuff! You won't see it right away, but I do suggest dealing with it right away or you will have regrets. That may mean digging up your clump and separating down to single fans to make sure you remove all the stolons. It's really hard to get rid of once it gets established. This is one reason that the classic "DF" is good- it's harder for surprise pests of all sorts to hitch a ride.
We hope it's a different, non-spreading grass, as that is much simpler to eradicate. Investigate and see. Once it gets growing, quack grass will clump at its growing points and these are relatively easy to pull, but the subterranean spreading stolons are the devil. It doesn't have a thick bunch of roots in one spot like other grasses.