Is it normal i'm never exactly sure when to ask for a phone number.

Yesterday, I was at Macy's buying jeans, and I don't buy jeans very often. The whole time I was looking at jeans, I was eyeing down the prettiest redhead I had ever seen. She was working the til and looked exquisite to say the least. She was completely filled out and looked absoloutly beautiful. I felt totally unworthy, but at the same time I wanted her sooo bad.

So when I was at the til paying for a pair, the cute redhead and I started talking about how we hate jeans that don't fit, and how she is lonely and cry's everynight (she was joking and stuff). She ran off quick and found me a better pair to try on.

I made my way into the dressing room and started changing when she came in and found me, and gave me a couple more to try on. I was making her laugh and she was trying to be cute'n cool and it totally felt way more like I was bonding with someone than just buying jeans.

Long story short.... After more conversation. I left without her number. I didn't even try, but she was so directly in tune with interacting me, I feel like I should have grabbed her number. There was loads of eye contact and laughing and I just really regret not asking for her number. Is it normal to not know when to ask for a phone number?