Is it bad that I didn't tip? (Strip club)?

The other day I went to a strip club for the first time. Not long after I entered, a dancer offered me a dance in the VIP room(which costs $20 just to go in) She could tell it was my first time being there. The dance was good. Before it was over, she reminded me what song we were on and said she didn't want me to go over whatever my budget was. (They charge on a per song basis for however long the dance goes). After it was over I paid the exact amount for how long she said it was. She said it was 9 songs and it's $20 a song, so she made $180. She probably could've (and maybe did)said it went longer than it did. I wouldn't have complained and would've paid whatever she said it was. Later in the evening when she was dancing for the whole club, I did give her a couple more dollars here and there and she definitely saw me do that and she seemed grateful. She said thank you and smiled. Should I have tipped her for the original, personal dance though