Stretch marks?

I've only gained 8lbs my entire pregnancy, I'm 33 weeks and the ONLY place I have stretch marks is my inner thighs. Did anyone else get them there? I don't understand why only because my thighs didn't get any bigger and they literally appeared overnight. I'm not complaining because I feel blessed to be pregnant but why there out of all places? They are so dark and I am so pale lol. Do they fade over time? I really want to be able to wear shorts again without being self conscious lol