Hi.
I really think it's luck of the draw - you could get a really tough quant section that's harder than OG, or you could get lucky and get one that's like the OG.
My first GMAT, I scored 690 - with only a 46 in quant. I found the problems to be quite difficult - I had serious trouble, and that's why I got 46.
I thought I could do better, since my practice scores on quant were 47-49.
I retook, got a 780 - with a 51 in quant. This time, the quant was a breeze. Every single question was EASY...easier than the harder questions in the OG.
So, I really think it's luck - if you do poorly on your first try but really think you deserve better, take it again - you might surprise yourself.