Is it reasonable for me to be suspicious of my friend?

I’m really iffy on this and it’s making me feel a little queasy lol!😭 Soo, to put this in short, I’ve gotten back with my ex that I’ve been friends with since the 4th grade (we were off and on a lot). During the time where we were on and off, I realized i needed to find myself and be able to realize that I don’t need to rely on others to maintain my happiness, and looks aren’t everything too LOL. So, yesterday night I told my friend I got back with him and coincidentally she just broke up with her (online) boyfriend. We ended up chatting for a bit about him and we brought up a new subject, COOL. I’ve noticed in the past few days even before this, she’s been like snatching my phone— constantly trying to read our messages. (me and my boyfriend) I dismissed it, seeing how she’s done this before and it’s not really a big deal. —Until today. Today, she did it CONSTANTLY— even when we were on an entirely different conversation, for example. I was trying to open Duolingo, noticed it was taking long. She taps my phone, and asks to see— not thinking she’d do anything but reload it. NO, she grabs my phone and tries to open the message app to read my messages. She did it again in another class, but quite literally running from me when she had my phone for the entire start of class. (looked in iMessage & TikTok) I thought it was nothing, until I noticed she literally found his account from mine and was “stalking” him or something.. He’s not a big social media guy so he clearly doesn’t have anything but still I thought that was weird, and I’ve been thinking about it all day— even talked to another friend about it soo.. do you guys think what I thinks going on. TLDR: friend recently broke up with her own boyfriend and had a seemingly new fascination with mine (stalking our personal messages & tt messages and his TikTok page)