Can they get too much catnip?

With Raleigh vomiting so many times today, I tried to think of something she may have eaten... the only thing I can think of, since she's an indoor cat and when she does go outside, she stays on the porch, is catnip.
A few days ago my husband took a fuzzy toy and put it in a bag of catnip and shook it around... then let the cats have it. The next morning there was a small green pile of vomit next to the toy... can cats get sick from too much of it, or can they be allergic to it?

I am sure if Raleigh ate too much catnip, she might throw up - but also, keep in mind that some bugs can cause an upset tummy. what kind/color of vomit is it?
I would watch her, and if she continues to throw up, call your vet - better safe than sorry!