Having a fast (6 minute or 3.2 km) assessment run in the week leading up to a race is not uncommon, and certainly nothing to be concerned about. However, it is out experience that the system very very rarely plans them within 3 days of your race.
We know that in such situations, some people prefer to skip the assessment, but we do encourage you to keep to your plan if possible. They are not detrimental and are beneficial for your overall training.