Concern is too strong for me, maybe just "be aware". From Nick's opponent's standpoint, they should be just as aware of Nick's ability, as he's jumped a level. Wrestle his (Lee's) match, and let the chips fall where they may. Heck, McKee had Lee in trouble too -- no panic at all, just roll through and come out on top, but Nick still needs awareness to get out of positions he's at a disadvantage.
I remember coach saying (paraphrased) - if you're in a position that isn't comfortable, get out of it asap, as it's probably one that's comfortable to your opponent. It was said at one of the Coaches Radio Shows.
Pletcher (short, stocky, and quick). Lee took a period and a half to get through Pletcher's defense, and Pletcher's early takedown (first given up by Lee in a dual this year) was a thing of beauty. Good fight by Nick to weather the storm, and dominate last half of the bout. Still think it's slight advantage Nick going into Big Ten's, but anything but a pushover, same with NCAA's, if they meet.
Demas (strong, like's throws). Lee wore Demas out at NCAA's last year, but Demas had a large lead with the two throws. Lee is certainly aware of Demas' strength, and may tweak his style, but still needs to wrestle his match. Lee's level jump should show in a rematch if it happens, and I would expect Lee's fitness to again play a part in the bout.
EDIT: Just saw SJP used the word "aware" too. Great minds...?