Punishment for lying, do you think I was too harsh?

My 4 year old daughter has been telling lies a LOT lately. Big things and little things and I've really had enough of it. She usually gets time out and loss of privileges. Well earlier today I took her and her younger sister on the train to the Zoo. Sophie had been in trouble earlier in the morning for various things (she's really pushing my ons lately!). I warned her before we went out that any misbehavior would end up in us coming straight home. Well all the way on the train she wasn't listening well, then when we got to th Zoo she started asking for ice cream. I told her after lunch she may have one if she stopped asking. Consequently she threw her lunch in the bin when she thought I wasn't looking, then told me she'd eaten it when I asked her. So we went straight out of the Zoo (we'd only just got there and hadn't seen anything) and she came straight home to her room. My husband thinks I was too harsh but I think she really needs to learn to behave and to stop lying. What would you have done?