I think in general at this range the Euro tends to be far more amplified with most storms than the GFS. In terms of it being a well-known bias, I think maybe only recently as the Euro used to have incredible verification scores back in the day in the mid range.
They tinkered with it a little and now it definitely is a bit more overzealous in the 4-7 day range, whereas the GFS is the opposite extreme. Doesn't mean either one is right/wrong this time, but I don't think the notion should be completely discounted.