Age gap? (27 and 20)

My very close friend and I have recently started having sex. We've communicated about our situation and aren't in a committed relationship

​

We met studying the same course in University (I was 24, she was 18). At the time I was in a long term committed relationship (8-years)

​

We became good friends over the past 2 years. And, especially since my break up, we've gotten very close and have been spending more and more time together (meeting multiple times a week, texting daily, sleeping over etc.)

​

We've both always been very open and communicative. Including regarding our relationship. We both saw each other only as friends, and encouraged each other to seek out other people

​

A few weeks ago, things took a shift and we started having sex. Again, we've discussed and communicated our feelings and what our relationship means. And we're both still on the same page

​

I do, however, feel unsure about the age gap in our relationship. It's never an issue that comes up, but I won't lie it's something that's always in the back of my mind

​

What are people's thoughts?