am i over reacting or can she have a boyfriend? she wants to meet up on saturday?

[Fred]

I went to the grocery store and met this girl who worked at the deli, she served me once and we joked around while she was serving me. The next time i went back she saw me in line and said hi to me and we flirted for a few minutes. The next time i went back she said hi to me and someone else was serving, so she switched with them. She was really nice, she got mad at me for wiping my hands on my shirt after i tried the samples she wanted me to try because they were her favourite, so i had to use paper towel she gave me. We flirted for around 30 minutes, and i asked for her number. I called her the next day on saturday, and seemed excited to talk to me. We talked for about 10 minutes because she was shopping with her friend. She wanted to meet up on the upcoming saturday, but we didn't make plans. I called her on monday, and she didn't pick up. She texted me an hour later saying she was doing homework with her friend and he wouldn't like it if she talked to other guys. I found it so weird, but i showed it to my friend and she insisted it was fine. I don't know her well but whenever i talked to her she seemed interested in me. Am i over reacting because i'm a guy or is it weird?