Jon I had a similar issue with my old GS, it was -12 outside though.
Battery took forever to fire the engine into life, is the bike kept outside overnight? I know this can affect the battery on these quite badly, when mine was garaged there was no issue but a couple of nights out in the cold and it didn't want to know.

Mine was the battery dying even though it was 2 months old, dealer replaced it FOC but yours might be a different issue.