Mucus plug reaction

Has anyone mentioned a mucus plug to their significant other and they act really disgusted? I was surprised because he isn't usually grossed out about anything and doesn't act immature about most things either. I just wonder if he is starting to get nervous about birth or something? I told him I thought I was starting to lose my mucus plug and he didn't know what it was so I briefly defined it. Then he asked why I would tell him something like that and said that ruined sex now and that that was disgusting.. I get that it totally sounds gross but geez!
Later I told him it was basically like a cum booger lmao. At least for me because it just seemed to be a little bit of it, not all of it. It didn't make it better. Even though he said it was the plug that was disgusting it made me feel disgusting. I guess I'm sensitive but it hurt my feelings. I wish I wouldn't have mentioned it now but I seriously didn't expect him to be grossed out. We always talk about gross/weird/gory stuff and he hasn't acted immature about anything during my pregnancy either. He keeps acting like he will be totally calm and cool during birth and says he will be able to watch the whole time.. But after this I'm thinking um you probably better just stay up my head. Maybe all of this stuff is just becoming super real and scary for him as it gets closer, I'm due June 3rd and this is our first but what about me?! Lol. Sorry, I had to vent. I'm trying not to be in a bad mood right now but that totally put me in one.