Hedgehogs do not always hibernate throughout the winter, coming out now and again at warmer times. During hibernation they wake up about every 7 or so days to come out and forage.
If a hedgehog is seen out during the daytime it is in trouble and will need help. Put in a deep box in a warm room with some cat/dog food and water and contact local hedgehog group or rescue centre.
Do NOT give it milk just water.
Hope this answers your query.