Should I have tipped? I’ve been thinking about it

So I went to this beauty bar that offers teeth whitening at half the price of a dentist office, they came out great and the lady was SUPER nice to me the whole time, giving me compliments any everything. At the end, I reminded her I paid in advance and then she said oh wait tap the screen if you’d like to live me a tip and the amounts was outrageous. I was so off put by the situation like I already paid and she stood in front of me to see if I would tip. I didn’t bc wtf kinda awkward and who tips for teeth whitening? Or am I wrong? I always tip bc I know that’s how people work for money and I used to as well but it was just so awkward like I feel like I shouldn’t have been put into that awkward situation