Flinching with Daddy

Ok, so I'm going to sound like a crazy lady - Bare with! 😅 So, the last few days my partner has raised an issue of our 6 1/2 month boy flinching at him. I missed it a few times then I saw - I thought it was more of a squint, never seen him do it before! I am 100% confident my partner hasn't and wouldn't hurt him. I'm stressing that maybe I've not been seeing it? I'm sure I would have, it raised such a flag and shocked me as I hadn't seen him do that before or pull the face - A squint type face. I had a shower earlier, my partner watched him. I came out, he looked in shock I asked what was wrong, he said "it happened again. I don't know what I've done to make him do this with me. I can't get him to smile. He hates me" (our boy is having a bit of a fussy period at the mo) ... but, I've seen him do it a few more times tonight. I thought at first maybe it's my partners beard, he does flinch when he kisses him on the head (I don't blame him) but it's mainly if my partner says "Can you say......" but he doesn't do it with me?! It's SO weird. I've made the mistake of googling it... now I've read things that will have me up all night watching the monitor closely 😅 Do I need to speak to the doctor about it just in case? I haven't managed to get it on video so might sound crazy... Anyone experienced this or similar? 😔