I just planted a new maple tree 3 weeks ago and the leaves are all droopy, every single one of them. Is this normal for a new tree?
The image looks to be quite normal leave structure appearance, but if the tree is droopy, it may be thirsty. Make sure the entire root system is receiving the water by deep watering over a longer period of time.
Make sure the soil is moist but never soggy on new plantings.
Keep the mulch away from the base of the trunk, this can lead to diseases.
Here are some links with more information.