Did i freak out my girlfriend?

We were makin out and of course like every guy i got horny bcause she was on top of me bt i dont know if she felt it or not....well wen she got off to stand up i immidiatly hid it so she wont see it bt i was still layin down and we started talkin and she kept starin at my crotch the whole time till we started kissin again...why did she keep starin,is it cus she felt it and i freakd her out,i dont think she did bcus if she would have she would have gotten off imidiatly right? But yea the point is why she keep starin n did i freak her out?