Based on what I've read here, I'd say there's a good chance there's an actual problem.
But, please read and understand this one thing: the initial GS at the start of the season is the very lowest end of respectable. Not understanding this feeds hysteria every new season.
Here's an example of what that means:
Imagine you had 9 players who played between 48 and 72 minutes, and 3 went to average, 3 stayed respectable, and 3 went to strong. It might look on first glance like there was an equal spread of GS increases and decreases. But in fact, the 3 averages went down less than a full level, the 3 respectables either stayed put or much more likely went up as much as just short of a full level, and the 3 strongs went up more than a full level.
Anyway, that all being said, I'd put my money on there being an actual problem this week based on a couple of reports above from reliable users. Myself, by the method above, I had 9 ups (4 to strong, 5 respectable) and 2 downs (to average) among my 11 players playing "optimal" minutes.