I am level 38 and I still have not passed vigrid roughland. should I be concerned
No, I wouldn't be terribly concerned. Grizzleheim is a world in which a wizard can move at his or her own pace, in her/his own time. It isn't directly tied into the main story line, so none of the quests are essential to gaining access to other worlds (except for Wintertusk, but that comes later).
I would suggest that you finish Ravenscar around the time you hit mid-way through Dragonspyre, and plan to do Wintertusk in tandem with Celestia. That way you will gain gear, stats, and spells pretty evenly with your level increases.
The benefits to focusing your efforts on Grizzleheim and Wintertusk become more apparent as you become familiar with the story lines. The power and generous XP you will gain in WT will definitely improve your Celestian experience, and you will notice surprising links with Zafaria when you get there.
Whatever you do, don't stress about it, and have fun!
I never start GH until level 40 or so. I began to quest there at level 20 with my first wizard, and found it too hard. After that, I decided to start it when I finish Mooshu. That has worked out well with my subsequent wizards--in my opinion, level 38 is just fine.