Yes, you should have.
What you’re looking for here is meaningful interaction. You both felt a spark when you locked eyes, that provides the context, that there’s something romantic there you want to explore.
She even opened up the space by saying ‘hi’. This isn’t a gift you’ll receive very often, when you do get it, you should really try to make the most of it.
So start talking to her. The meaning behind the conversation is the spark you felt when locking eyes, it’s the whole reason why you guys are talking. People always wonder what you should say in this context, but it really doesn’t matter a bit what you’re saying, because the point is to fan the flames of the spark.
If you need some basic guidelines for what to say, then remember that you’re in a store and you need to keep it friendly, but trend towards romantic. The context is friendly. When you’re in a romantic context, like, say, a dinner date, then you can trend towards sexual. But unless she ‘goes there’ first, don’t try to seduce her the first time you see her. Keep it in your pants, Romeo.
The idea is you’re teasing her, giving her a little taste of what it would be like to spend more meaningful time together. If you do it right, then the rest of the world fades away and the only two things in existence at that moment are you and her. This is romance.
But you’re not there yet, so you have to be friendly. When you’re with a friend, the rest of the world exists and you guys are exploring it together. In this case, the store. So you might point out weird things about the store and make jokes about them.
In romance you don’t explore the world, you explore each other. So talk about her, and yourself. Display your personality a little more strongly. Say what comes off the top of your head, unfiltered.
If you still like her when it’s time to stop interacting, ask for her number. If it started with a spark, and the spark turned into a fire, you won’t have to ask. She’ll be shoving it into your phone.