Letting it sit a few more days won't hurt anything. 10 days ought to be enough, but some yeasts and some recipes may take longer to finish.
Also, Extract brews are renown for finishing high for whatever reason. If this is an extract brew, you might not get the FG you expect. Take another reading in a few days and see if it's gone down any.
A Hefe I'd probably consider "done" in 2 weeks if the fermentation temp was TOO low (That can slow the yeast down and make your fermentation take a while longer.)