Should I be worried that she didn't message me back?

[James]

I did some little flirting with her on facebook for like a week (I liked her new profile picture, we had a poke war, commenting random google images on her wall for like an hour lol, etc) and then Monday she poked me, and I poked her back, but now she hasn't poked me again since the (she's usually almost never on during the school week though, last week was weird). I wanted to ask her to hang out this weekend sometime, so then two days ago (Thursday) I saw her on and I said "hey loser" to her on chat, but she didn't reply and it turns out she didn't even see it until last night (Friday). Should I worry that she didn't message me back? I mean I wouldn't message someone back a day late if they just said "hey," so I don't think so. And should I try messaging her again tonight or should I wait a day or two longer?
Thanks
PS I know that just because I flirted a bit with her doesn't make her mine for the taking, but it just seemed weird that she abruptly stopped all contact.

[Sunshine]

just wait it out a little while, girls are weird like that, dont be too clingy or we'll get scared off.
honestly just wait, and talk to her at school, or get her phone number and text her, because facebook chat is also kinda lame, she will like that you have taken inniciative. good luck