Hi OutoftheWoods,
I'm going to hedge my bets and say your ex is talking about you to the replacement and likely creating a veil of "jealousy".
This is all to affect the replacement, not you. To manufacture jealousy.
My ex was a pro at this. To this day she tells people I contact her and am stalking. I haven't seen, spoken or emailed my ex in close to four years. I avoid social situations where she might show. The scary thing is my ex is an amazing actor and people truly believe I'm insane. I have to be careful not to look at someone the wrong way or they will consider it harassment, just based on what people have been told about me.
After NC on your part, for this replacement to approach you like this tells me your ex is indirectly trying to triangulate. If you haven't responded I suggest you don't.
There was one point in my relationship my ex told me she had a restraining order on the woman before me. Funny that three weeks into our relationship she was calling this person for advice on electrical wiring.
If things seem fishy, and this seems fishy, don't acknowledge. Any response is like talking to your ex. Seriously. You have all the power.
I'm sorry you are dealing with this. You were wise to post here first.