You might have noticed a carat symbol next to your Price/Unit when you are assigning resources or roles. This usually happens because of following reasons:
1) Role has been assigned to the activity
When Role is assigned to the activity Price/Unit is taken from the default settings of the project.
Assuming the default for the project is 1/hr
When we assign a Role to the activity, it picks up this rate and a carat symbol is displayed
2) Rate source is Role
If a Role has been assigned to a resource and we change Rate Source as Role a Carat symbol is displayed again