I planted this Grimes Golden 1-year-old tree this Spring. Zone 6b, 7a. Our weather has been unpredictable with some very warm days, but we've already had several below-freezing nights/days and some nights in the teens. It seems the other two branches/"trunks" aren't even growing leaves, but this shorter center one has a bunch it won't let go of. Do I need to be concerned?