I have seen this fine particals in lots of cars... May well turn out to be a problem over time... but odds are it will not.. As long as its not chunks.... I have had them have a fine partical in them the first change.. and never again ... and drove them hundreds of thousands of miles.. If I were you I would run it a while.. and change it again... the next time it will also have some particals in it as some were left inside the last time.. However it should not be as bad... If its worse then worry about it.. However for now I would just put it on the must change oil a few times list..

Ken