Am I paranoid - jealous or do I have a legitimate concern?

So this is my first ever post on a forum so bear with me....

I met a woman about 3 months ago she is 33 and I am 30. For the first 2 months lets say it was casual (I was not seeing anyone else and neither was she although she was chatting to others) but we had not had the chat so fair enough.

About a month ago it was agreed we would be exclusive and I know she stopped chatting to others, although I know she still has tinder on phone - but OK I don't think she talks to anyone.

Last week we went for a lunch together and she saw a guy from tinder she was chatting to up until we went exclusive - talked about him for 5-10 minutes.....OK no problem. That evening she says to me - oh I messaged that guy hello how is he doing etc - he replied and then they started to chat a bit since then.

She is also still chatting to another guy from tinder an old match suddenly as well which she had not spoken to in 2-3 months because her mum saw a play and he happened to be in it. - so far the chats seem innocent enough but regular chats/messages

I just think - she has never met these people before - met them online via tinder and if she doesn't plan to engage with them romantically why would you start chatting again.

Maybe I am over reacting and I am trying not to be a jealous loser but her history also worries me - she cheated on ex husband although he seemed like an idiot (her side of the story) but she went on a girls holiday - cheated then began a 4-5 month affair with the guy until the husband found messages on the phone and gave her the boot it seems.

So the history mixed with these messages - is kind of playing on my mind a little - I did try and mention it but we have only just been exclusive a little while and she says relax if someone is going to chat they will cheat so don't worry about it.

I don't know if I should just wait and see if she meets one of them - if so id stop seeing her or just outright ask her but this will make me look unrelaxed and jealous and I know this would be a massive turn off for her.