if the nodes are too tight, give less light and it should stretch more -- in a healthy way. The older internodes will stretch slightly, but mostly you'll see this on new growth. the old stuff will still be too tight.
if this is the case and they've been burdened with too much light for along period, it may take a week or more to get out of that funk. if light is causing what you see, it won't stretch until you give less light.