Why does it fees like shes avoiding me when she showed so much interest in me before?

We had our first date 2 nights ago. It started off good, got a little rough part way through (she got a bit too tipsy and I had to take care of her), but it ended on a really good note the next morning (a lot of talking and kissing). She text me literally 15 minutes after I got home apologizing for doing what she did last night, even though she said for me to text her 2 individual times before I left her place. We both agreed that we wanted to see each other more, but yesterday I was texting her and she just randomly stopped texting me. I messaged her on FB tonight and after like 4 messages she just stopped messaging me and logged off. I know she's a really busy person, but you'd think she'd give me the common courtesy of telling me she's busy and has to go, since I do when I have to go do something. Do you think she's getting annoyed?