Ex's gf working with me

So I found out today that my ex's (my sons father) gf is my new co-worker. I work as a custodian at a high school and I've been at this job for 6 months and my ex knows exactly where I work because he works at the middle school right next to us as a custodian.. So we got a new girl who started yesterday and I didn't meet her til late last night because she worked 12-8 and I work 2:30-10:30 every day (that's her new schedule as well) and I said hi and introduced myself and went on about my night and today she worked 2-10 and we had some small talk and did our jobs.. Well around 9:30 I noticed that my ex's truck was in the parking lot and I thought that was a little weird but didn't think anything about it.. I went out around 10 to get my charger from my car and she followed me out and I noticed she got into my ex's truck and they drove away and I was like wtf and then I remembered his gfs name and realized she has the same name.. Let me just say I know of his gf and I've seen glances of her but since I avoid him and anything that has to do with him like the Plague (I literally only talk to him about our son) didn't remember what she looked like or even her name because that's how much I don't care about what goes on in his life lol.. But I find it weird that she got a job at my place of work when there's currently like 4 openings at other schools for custodians (even his school is hiring) but she gets a job at mine? He knows this is where I work.. Now that I know this I feel indifferent about it.. Is this strange to anyone else or am I just over thinking it? I personally don't care because I don't come to work to make friends (I'm only friends with a 60 year old man I work with lol). I work and go home.. I just think this is too much of a coincidence..