Older woman likes me? What do I do?

So... There's this girl who works at the smoke shop down the street from me, and she has been really nice to me recently. (employee discounts and just chatting for about 30 min. A visit) and I always thought she was cool. Well she added me on Facebook, and gave me her number and said we should hang out. I figured she likes me, so I asked her to stop by after work for a drink. she said yes and we talked and stuff and Ive decided I really do kinda like her. But she's all mature n stuff cuz she's 26, and I'm only 20. But I have a job, I live on my own, I think I'm reasonably mature. She texted me saying she wants to see me again, so I was thinking about asking her to a movie because I got two movie tickets at work for winning a promotional drink sale contest. Is that still cool if your mid 20's? Or is it too childish and lame? I know she's used to going to bars n stuff with her friends but I can't do that cuz I'm not 21. Are there any other cool things I can take her to do that aren't awkward "this is a formal date" scenarios? Or is a movie a good choice? Help I'm freaking out!