Hi Howie,
Hip flexion is something my surgeon advised not to force, surely for the first 6 weeks but also to be very careful in the months after. In his experience, problems in the groin are mostly because of overdoing.
I had discomfort / mild pain in my groin that creeped up around 3-4 months post op, he recommended to avoid hip flexion exercises and take anti-inflammatories for a couple of weeks, then go very gradually.
My physiotherapist found hip flexion was the area where the operated leg was weaker than the other, but agreed that I should not force and give it time, as 3-4 months it's still not much in the big scheme of things, and there are surgical reasons that explain why (someone posted about that already).
I was not totally convinced to be honest (we tend to over think the little pains) but followed the advice and now I don't have that discomfort. Still it's the weaker area but I'm doing the hip exercises well again and swimming is helping.
I'm almost 6 months post op and, in spite of feeling great already, I still see big gains to be made. So 6 weeks now seems very early days.