Female friend said something about my girlfriend which left me feeling very weird/uncomfortable

Hi everyone, I?ll start this off by first prefacing a few things. We are all 23.
My female friend,Let?s call her A,I?ve known her for almost 5 years now and she?s my best friend?s ex. Me and her have been good friends and I have ALWAYS upheld those boundaries. There were scattered events where she would flirt with me but I always ignored them and expressed disinterest.
My girlfriend of 6 months,Let?s call her B,She?s Legit the most amazing person ever. I love her deeply and I?m extremely happy with her.
So A and I don?t talk TOO often,We speak on call maybe once or twice a month. Recently over one of said calls,Everything was going great. A was excited to meet B and the conversation was great,We spoke about careers and what not. Towards the end of the call I told A that I?ve to go as I?ve to call my girlfriend (B) and talk to her too,B is in a separate time zone currently so hence. That?s when A said something that REALLY weirded me out and frankly made me a little uncomfortable. She said ?Oh yeah you have to talk to your other girlfriend too yeah? and I audibly went ?Uhhh? before saying Bye and ending the call.
Is this weird or am I overthinking this a lot? And I do plan on bringing this up to her and would appreciate on how to bring this up with A.
Tl;Dr: Female friend said something that seemed slightly flirtatious and it has made me slightly uncomfortable.


Source.