Should I be worried?
I made a thread about this a few months ago, I was super worried when I changed my oil after cam break in. It looked pretty much like yours, and I had a little bit of crap on my magnetic drain plug. First oil change I had about 4-5 little slivers (really tiny pieces of crap) in the oil filter, next oil change the oil was better but still kinda dirty, oil filter had 1-2 slivers and my last oil change looked really good, the oil was fairly clean and the inside of the oil filter looked brand new. What I was told on here and by my machine shop was that most of the glitter is from the rings seating and many other things seating. The colour is also caused by ARP bolt lube, cam lube and whatever other lube was used inside the engine. For my motor I had used a whole bunch of ARP bolt lube, it took a while for that to clean out. I remember after the second oil change I still had some on the head bolts under the valve covers.
I went to my machine shop and asked him about it, he told me that as long as it clears up and oil pressure doesn't change there shouldn't be a problem. Now if you keep getting pieces of metal or they seem to become more apparent, and if oil pressure starts to drop I would be worried.
Currently my motor has about 2000 miles on it, oil pressure has been completely consistent and it runs like a champ! I have still been adding a zinc additive as well just to be safe.