Her Vagina Looked Flushed...

Im 36 years old and have been with my girlfriend for 6 years. 3years ago we had a baby girl. Too give a back story on her real quick. Her Grandpa raised her because her mother was a flunky. Her mother also had numerous men giving her money. U get the idea.. my girlfriend is 10years younger and I heard a couple things about her when I first got with her. We get along good. But...I took a job working out of town all week and one week I came home. We both took showers and started foreplay.I noticed that her vagina looked soar (slightly flush) and opened a little. Everything just seemed different. This was a year ago and I have never mentioned anything too anyone. I just want too know if she could have ppossibly had hard sex with someone else that day or late night before. I didn't think she would do that and have sex with me not long after but I've learned that u can never be too surprised. Although it surprised me. But honestly I've been through this plenty of times in past relationships and it doesn't bother me like it used too. I need some opinions of similar situations.