I don't think so. Yeah it's not the greatest sign but it's still not really that bad. Unless a girl is totally into you I wouldn't be surprised if she would want to think about it before giving a final answer.
Take it from the psychological perspective,..First use some body language (confidence!!! but don't use the usual pimphustahplayer type of language) but use some common sense,, tell her that you like her (color)eyes (even if she has a nice body), then start talking to her about her things (stay away from themes like cars, sports, friends, chicks or any other type of themes that can spoil your chances), pretend that you care about her (if you do, then you're on the right track), she'll notice that and think that you are charismatic and intelligent...and just at that moment bam!!!!! you leave ...why? cause you need to save some tricks for the next time, you're gonna place her into the stand by zone.(have you ever listen to this old crap "I don't kiss on the first date"??? BUL#@$T, she wants to know if you're into her or not..so play with the same card! be smart...
Call her for a second date, start with the same strategy but instead of leaving you go for the prize.....works almost every time, not matter who you are!!!!
ill think about it doesnt mean that your friend zone per se but most likely but still like others have said not a big deal just yet
from my experience (to the you the truth its very limited, only been with my current and well only "official" gf), you never want to wait cuz she wont make the first move unless she is absolutely into you (as in my case, i liked her but was a ***** and didnt say/do anything, but she kept pursuing me so that I got the idea, asked her out very cheesily but hey it worked and now weve been together for 10 months, and already plan to get married lol not anytime soon though)