You cannot compare raw state margins in this election, since Obama won by 7%. That would be like saying in 1984 that Massachusetts was safer for the GOP than Minnesota for the Democrats.
I will say though that what really surprised me was Michigan swinging towards Obama compared to 2004. I certainly didn't expect that. Overall, it seems like what really made Obama in this election was the financial crisis which seems to have pushed blue-collar white voters (outside of the South) heavily in his direction. Michigan, Pennsylvania and Ohio all seemed to improve substantially for him towards the end (as did some other places like Massachusetts).
Still, compared to national average we're still not talking about a state that is safely Democrat. It was something like D +7 or +6 - in other words about as Democratic as Virginia was Republican 8 years ago.
Huh? Michigan was D+3 or about a 6 point margin above the national average in both 2000 and 2004. Now that margin has grown to about 9 points or so and MI in fact not just swinged, but trended towards Obama.