I agree with you OP. I think that falling into that complacency - oh it's just men being men - in the workplace can be a slippery slope. Guys are better at this, women better at that... I don't think there is necessarily harm in little details here and there (a smaller female nurse needing help with turning a large pt), but aren't we beyond sexist generalizations by now? I mean sure, some hubbies don't like to change dirty diapers. We aren't at home and our male coworkers aren't our hubbies.
I don't think that work is the place for sexist, racist, agist, etc... generalizations. Even if he didn't mean any harm and was just joking. It's off-putting to all of the women not getting a pat on the back for doing the same job.
I don't think I'd make a big deal about it. If it was something I heard a few times I'd speak to him. But maybe that is me just being a little too complacent about standing up for what is right.