<human>: I met a girl on tinder and we have been hanging out for about a month and a half now. She has always been saying that she really likes me and wants to date me. But I always told her that I was not emotionally ready for a relationship. 

Fast forward to two nights ago, she brought up topic of dating again and this time I agreed that we should date.

Ever since we started hanging out she has been really sneaky with her phone. She would be texting people and suddenly hide it if I walked into the room. She will be talking to guys on the phone and if I asked who it was, she would say some female name like Sarah etc. This did bug me a little but as we were not dating, I did not say anything.

Last night, after we had sex. We were both laying in the bed and I fell asleep. I woke up a little later and she was using tinder on her phone while laying next to me. She just froze and tried to tilt the screen so I could not see what she was doing on her phone. But I had already seen. I did not say anything to her and pretended that I was still half asleep. But I feel it was disrespectful of her to be doing that. 

I have been cheated on before and I am not sure if this is a red flag or if I am over reacting?

Give me the gist of the text in a nutshell
<bot>: Started dating my FWB. Found her using tinder while she thought I was sleeping. Is that a redflag?