Every fermentation is a little different. I've had kraeusen stick around for 3 weeks, others that disappear in 3 days. It's all "normal" - the yeast are following their timetable, not yours. The type of yeast, the recipe, the temperature, all have an effect.
Like Matt said, don't push it, check it in a week or two, and let us know!
"Anything worth doing, is worth doing slowly." ~~ Mae West