What did AR think of it?
MPs don't always have the adversarial relationship that the public tend to assume, even across parties. There was one MP in my country who was widely considered to be an aggresive blowhard by the public, I was quite surprised to find out that civil service staff thought he was one of the best MPs to work for and he was really popular with them. My point being I wouldn't assume I understand the specifics of what's going on in an interaction like this.
I don't think it's necessarily the case that because a social interaction is different between opposite sex people than it i between same sex people that it is sexist. But winking is not very parliamentary in any case. But I'd put it at the level of a minor bad judgement rather than something more serious.