Unlikely, but plausible. The problem is the survival time
in space while being subjected to cosmic ray bombardment. How long could a life form survive in a chunk of rock versus how long might it take before said chunk of rock impacts target. It is really tough to make the call. It is possible, for sure, at least within the Solar System, where transit intervals might be small, in principle. It seems to be impossible in the interstellar case, because transit times would be on the order of millions or billions of years.