Nic,
Try to remove the particles either by toothpick, toothbrush, or something else and see if they are able to picked up with a magnet. If the particles are attracted magnetically than this may indicate something that is serious, maybe bearing race, cam, cam chain, gear, etc.... More than likely what you will find is that these are not a magnetic metal and is more than likely from the cam chain tensioner, clutch plates, or the casing of the bike probably from the cam chain area. If this is the case, these kinds of metallic flakes are common on the Husabergs and can be less serious. What ever the case, you no that you have some wear inside the engine and that is important to know as you do maintenance on areas of the bike and can now use this information to start planing preventative measures in the future. I would probably recommend looking for a new cam chain tensioner, cam gear (old ones are aluminum and should be upgraded to the more robust steel type) and think about replacing these sometime in the near future. If the particles are magnetically attractive than this may indicate something along the lines of bearing failure. If this is the case only a thorough teardown with meticulous inspection may be needed. Others may add comments with their suggestions as what to do but at this point I don't think anyone would be able to diagnose the culprit with certainty. I have some spare side cover gaskets it you need one to pull and inspect but you would also need a water pump gasket and some threebond 1211 or similar sealant. I don't think you will find much on inspection of these parts but thats just my thoughts. I find metallic particles on my screen and filter after every oil change and have neither replaced the cam gear or the tensioner, I plan to when I feel it is absolutely needed or the bike just stops running. Hope you find the cause but I don't really think it's cause for alarm at this point.... maybe some pics of the size of the particles and letting us know wether they are magnetic or not would help.
Regards,