Yanbu, it's benevolent sexism. And it quietly hacks me off too.
But GOD FORBID you talk about this kind of thing on Mumsnet! It makes everyone do this "no no it's unquestionably lovely" dance, "my beloved X does it so it's fine".
Have we had the tinkly laugh "if this is the most you have to worry about OP then I'm jealous!" post yet? 
It's like there's this disconnect where people can't look past it to ask why the general principle of "you must be nice to women" exists, why men have had to be taught for centuries that it's polite to look after the little women, or why they don't do it for other men/women don't do it for women as a general social expectation.
If we think that women need that help or that men are uncontrollable animals without it, that's pretty sad.
And gosh no - wouldn't want to offend people with the word Feminist would we?
"Of course I'm a feminist. But not one of those ones, the crazies, you know, just the type who are accepted by men society. But even then, only if you're ok with it of course."