What's going on??

Meeting this girl next week I've known for a while for a date then back to hers. It's been going well so far but these last few days she seem so kinda distant and Takes like an hour Andrew a half to reply sometimes. We're at different unis but it's so annoying that she does this like I'm like what have I done? Meant to be meeting next Thursday when I get home but like whys she doing this??