Long time member here but been quiet since I haven't had a vintage mopar for a while.

Ran into trouble with a newer mopar and figured I'd ask here. I'm doing headgaskets on a 3.6 Pentastar. I bought new Mahle head bolts, sucked out any remaining liquid in the headbolt holes, lubricated the bolt washers with motor oil and started the nightmarish torque sequence. The final sequence is work up to 33 ft/lbs then 70 degrees followed by another 70 degrees. Some bolts will get to the final angle smoothly with just good effort from a breaker bar but others I have to put a jack handle on the bar and hear the head creak/pop as I'm getting to the final angle. It does not feel like the threads are binding (it doesn't feel like a torsion spring, its solid) it feels like half the bolts have a grippier finish between the bolt head and the washer despite the oil (maybe I should have used moly). I bought 2 sets of bolts and they were bagged slightly different, so likely different lots and maybe different finish (black oxide?).

I realize that torque to angle negates any install friction that would trip a torque wrench prematurely (would have definitely here) and I am confident all are screwed in the same amount, I am just surprised that some took so much more effort.

Anything to be concerned about if they are all torqued to the specified angle?

the creak and pop sounds that you heard would be concerning to me.
i would be wondering about how even the clamping load would be across the head.
if it were mine, i would remove the bolts and look for signs of fretting under the bolt heads, or perhaps the washers not having enough champher at the bolt head to shank to seat correctly under the bolt head.
i realize you will need to buy new bolts, but it would be cheap insurance in the long run.
just my opinion. your mileage will vary.

The creak/pop is almost exactly like if you ever had to remove lug nuts after a tire shop installed with way too many ugga dugga's. Just at the tail end of the torque sequence with these head bolts instead of trying to break something free. That's why I am suspecting the bolt head/washer interface.