I noticed this too. Especially the GFS. I'm not completely sold on it, but it's been steadily backing off the -NAO's blocking. 00z constructed a 564+ dm warm sector ballooned to the southern Lakes, E to our doorstop next Thur/Fri. That's not really a cold anomaly - it is in fact still a very warm one relative to April. Even if that warm air doesn't spill in here, it's not like it's aching hands on the cool side, either.
The other models are also backing off of the -NAO's, but still are colder in complexion. The Canadian being the most happy. The Euro has other days that are sneaky mild.
Overall, the influence of a -NAO circulation mode is coherent. However, the depth of the negative thickness ( the blue(cold) vs warmer(red) lines) have been easing off a little per runs