Today I found this spring bee in the garden, there are a few reasons that bees emerge earlier than they should. The first thing I checked is whether it had a stylops this parasite feeds of the developing bee so the bee doesn’t have enough fat to keep it going through to spring so emerges early but as you can see by the abdomen it doesnt have a stylops. Bees can become confused as in a long spell of cold followed by a warm period can trick them into thinking it’s spring, again this isnt the case.
So while I cant be 100% sure I would say this bee was disturbed from its slumber by a gardener who has dug its cell up forcing the bee to emerge early.
Most bees overwinter as fully formed adults that stay in their cell till spring.