Sometimes just the walk back to the house from unloading is enough to give it a little shock. Many are sold with that polythene wrapping to help protect them a little. Keep it away from drafts, or areas with lots of people traffic in the house too.
Thanks @richard.spicer.7906 @Dragon_Warrior and @treefrog44 . I bought several last week to do Christmas basket arrangements. They are in a light room, but not in direct light. The temperature fluctuats in that room though, so maybe it's that. I've moved them into another room now. I don't think it's a watering issue, but I gave it a big drink in the hope I would revive it (sadly not)