Wow, I can't believe how over dramatic the responses here have been, considering the ambiguity of the incidents you describe, which are very much open to interpretation. Many of the comments here have been incredibly vile and unhelpful. Thing I've noticed on mumsnet is that it only takes a few people to get the ball rolling, and then they all pile in.
You sound like a great mum and if anything quite over protective of your dd. You probably give your dp a much harder time than you would if he was your ds' real dad. Just as I think other posters here would not be so harsh.
Having said that, you're right to notice these things and talk to him about what's bothering you.
But seriously if this is the worst that you can come up with? And I have a feeling that you've deliberately painted these incidents in the worse light, not realising the responses you would get.
Yes, I understand how low level EA works but I also don't think anyone here is qualified to make such a diagnosis based on a few paragraphs.
The following are not making excuses for your dp, although I'm certain many posters will disagree and will be completely shocked that I'm 'sticking up' for him. I am just trying to take on another, very possible, perspective:
If she's been at her father's he makes a point of telling her what she's missed out on here
I think he should be told not to do this, but I don't think it's definite that he is doing this deliberately to hurt her. Maybe it's more of a catch up chat? This is very difficult for anyone to judge having not heard these conversations ourselves.
Re the cupboard under the stairs incident: If I start hoovering for example, blow me down if ds does't then need to get past me several times at that precise time. I tell him to wait, and if he trips over the hoover or I elbow him as I'm hoovering then I explain this is why he needs to wait. However, if it's to the point where he cries, then I would comfort him/apologise. But was this a one off - does he normally comfort her if she is hurt?
Re the pebble incident: Yes, it does seem harsh, on the other hand impossible to know for sure without having witnessed the incident and not knowing other relevant facts, for example, does he always tell her not to pick pebbles from the garden. As you said, he wasn't at his best after a 12 hour shift, and I'm not the best parent when I'm tired, been working all day and have PMT. We are human!
And who, hands on heart, can honestly say they've never had a conversation with their dc when all they've done is respond 'mmm'??
Tonight I was reading bedtime stories to elder dd and when we'd finished I was telling her 'the story of her day' as we do sometimes. She was giggling and we were cuddling and within a minute he was there plonking baby with us so we couldn't continue.
I honestly don't think this is a big deal, he might have thought you were having so much fun that he wanted the baby to join you? I'm sorry, but this is not an EA incident for christ sake! (aimed at other posters!)
I personally feel that it's hard to judge based on the incidents you have provided. I'm not saying the other posters are wrong. Maybe they're right, maybe this is the beginning of EA. Or maybe he is just a dad who love his dc but sometimes gets it wrong like we all do?
My only advice would be to talk to him about these incidents when you notice them. Keep being aware as you are already. And listen to your instincts, if you think something is wrong then there probably is.