Not a very sheltered place, but perhaps the cooling temperature caught her (or him) there.There aren't many large flowers around now to provide a better place.
Only the queen bumblebees will overwinter, in underground nests, so these worker bumblebees are just hanging out until frost.
Honeybees, however, will come out and forage on warm days especially in late winter, when the early ornamentals (winter honeysuckle, Japanese apricots, etc.) provide nectar and pollen, since they're on a different schedule than our natives.
