she's still a baby, and stuff can be scary. Can you take her for a walk? I would not be real quick to call her a nervebag for a single caution. It's a lot to ask of a 12 week old to not seek comfort when your standing right there. Just saying, I'd revisit after sleeping on it, maybe try it again. If you could walk with her, with traffic and comotion, it might be easier to judge. Not much to go on.