Different opinion......
If the powder still has a "new cloths smell" (dacron) or "doctors office" (ether) smell to it... it should be "ok".....
If it smells like "vinegar", then it's starting to go bad (like "old" aspirin). If it's 8lbs, only a modsest loss....(I had some 6lbs of 8lb container of H322 go bad.. I tossed it because I had some "old" H450 lock up the bolt of my '06 with a previously "accuracy" load--- well below published maximum. Case looked like a belted magnum when I got it out... without a primer of course !!!! ). If 80lbs, You ain't shootin enuf...... !!!!!!!!!
The deterrent coating on the H4350 is brown, hence the tan-brown cast to the powder compared to the black-graphite appearence of the IMR4350.........The dust is perhaps just some "excess" deterrent coating on that individual lot of powder. (variations do happen, just as they do with home-made biscuits....just becasue they're a "little too brown" dosen't make them bad..... unless they're hard as rocks..........
If it shoots "ok" and smells "ok", then I'd place the 8lb? container in the refrigerator (I keep my powder in a "replaced" refrigerator in the basement near the reloading area). If 80lbs, I suggest purchasing a "used" refrigerator to protect my considerable investment....... !!!!!!!!