I just got a fixed upper bridge about 3 weeks ago. in the top front tooth there is a little space. is this normal?

Hopefully not normal: Sometimes a temporary can push your gums too hard and the permanent restoration will need time for the gums to return to their original position. They should be doing that now. If the space is getting bigger than smaller, you need to go back and shoe your dentist the problem now.

Depends: Depends where the space is. If there is a space between the bottom of the bridge and the gum line then this is normal. This allows enough space to clean underneath the bridge. Please discuss this issue with the dentist.

Where is the space?: There are three possible areas for spaces. Between the end of the crowns and the teeth-there should be no space or opening. Between the edge of the crowns and the gums- it's only an esthetic problem if it shows with a smile. If it's a triangular space between the teeth at the gum line-it makes it easier to clean there but may not be esthetic. The space may or may not close in time.