Search Results: he only shows up when he has no girlfriend

Basically, this friend of a friend (let’s call her Mary) came to a graduation party we were hosting at my apartment. I hadn’t seen her since the last time she came to visit my roommate a few years ago, which was also the first time we met. Back then I had a crush on her, but right after that we both got into long-term relationships. She shows up to our party and starts acting weird around me the whole time. I’ll go in-depth about the specific moments, but keep in mind my girlfriend is at the party and her boyfriend isn’t, as he’s from where she lives (different country). She started our conversation by asking me about my musical interests and so we chatted about music and stuff like that. I noticed she started fiddling with her hair and maintaining strong, prolonged eye contact while we’re talking. She’s also standing pretty close, closer than I’d expect in a conversation between two taken people. When we broke off, she often stared at me as I was talking to friends, even while she was mingling with other people. When I’d meet her gaze, she’d continue to stare and smile until I broke eye contact. A little later I hear from my girlfriend that Mary has been talking to her about how nice I was to her a few years back showing her around town, which was no doubt influenced by how I had a crush on her. Mary would also do things like jab me to help me out when I wasn’t paying attention during a drinking game and laugh at all of my jokes. When it came time to walk to the club, it was raining, and I got wet along with everybody else. She turned to me and said “you’re so wet” and brushed off the rain from my chest and arms (my girlfriend was in the bathroom when that happened). Later on in the night when I was dancing with my girlfriend and being affectionate with her, Mary kind of stopped acting the way she did earlier that night. The next morning when she said goodbye to my roommates and I (she spent the night), I was the only one she hugged besides her friend.

My ex girlfriend and I broke up back in September, and it was the 4th time in 6 years we broke up because of religious differences.
Anyway, not long afterwards, I rejoined Facebook and made an Instagram. I met a awesome girl on Facebook and we dated until early March.
Recently, I've noticed that my ex of 6 years has been showing up in my suggestions on both Facebook and Instagram. Facebook, we have no mutual friends and I only searched her once when that new girl I dated wanted to see what she looked like. Other than that, we have not interacted at all. And she will show up if I go to DM someone on Instagram, but I made the Instagram hard to find. I gave her the username of she changed her mind about things.
My knowledge of the social media algorithms is on Facebook and Instagram, it's based off how much you've interacted, and it applies for viewing that person's profile.
On Instagram, even that girl I dated doesn't show up as easily or often as my ex.
Does this mean she has been checking on me?