tight stomach answers please !

So I just noticed today that my lower abdomen right above my bikini line is really hard. Could that be a pregnancy thing and if so how far along do you have to be to feel this ? I'm 130lbs and 5'8 so I'm pretty thin. With my first child I was a lot bigger so I don't remember feeling that. So anyway I feel like this is all new to me again sorry for asking so many questions lol. Thank you all for the support !