Honestly I think this is more common than people admit, especially in those quiet, cozy moments when you're settling baby down and everything feels so calm and safe. A few of my mum friends mentioned similar things, like they suddenly understood why babies find sucking so soothing, and some of them caught themselves doing little self-soothing things too without even realising it. It makes sense lah, because you're in this deeply nurturing headspace and your body just responds to that same comfort. You are definitely not a weirdo, you're just a mum who is very tuned in to her baby.