Depending on how you define a civilization its probably very likely. Is it having cities, towns, peoples, songs, cultures? Or, is it merely being able to make use of resources from an environment at a large scale? With the latter definition, a mychorrizal network looks a lot like our own civilization. It expands and contracts, takes advantage of resources present in the environment, influences that environment for its benefit, and adapts to changes in that environment. All behaviors that, with a big step back, are identical to the hallmarks of our own civilization. Life like this could certainly seed an entire planet. It is certainly possible for spores contained under layers of ice perhaps to be smashed off of one planet, drift into outerspace, and eventually crash into some other planet, and should the conditions be right, seed that planet with further life that itself undergoes further mutation, selection, and evolution.