Husband and their ex

This might sound silly but I'm a hormonal insecure mess over here
My husbands a gym freak his a body builder and goes to gym everyday. The gym his been going to for the past 10 years is closing down so he changed gyms . The new gym I noticed is his ex used to go there (unsure if she still goes) but she gave us trouble at the start of our relationship and I don't like her or trust her. I asked my husband if she goes there and he said he doesn't know he didn't see her 
I don't like him going there. Simple it makes me uncomfortable 
What would you do in this situation?

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