A hug in front of other staff, other children and parents is not a dangerous thing.
No, no, no. Did we not just see an olympic doctor convicted at trial for abusing girls in his care in plain sight?
When a child predator grooms, they do not just groom the child, they groom everyone around them.
This is attitude is very dangerous. It has enabled people to get away with abusing children for decades. It has to be challenged.
I'm not saying definitively that the man in question in the OP is a paedophile. I'm merely pointing out that it's incredibly naive to think that child abusers only do it in secret. The normalisation and excusing of the grooming in plain sight is part of the MO.
Red flags for people with an unnatural interest in children are:
Number one - wanting to spend a lot of time with children, over and above a 'normal' adult tolerance. Children are testing, and exhausting. It's natural to want a break from them after a period of engagement with them. Any adult who actively seeks out the extended company of children and doesn't appear to tire of it normally, especially if the company is in a one-to-one setting, or away from other adults: that's a massive red flag and should be paid attention to.
Number two - if, when challenged or asked to change their behaviour, that person becomes defensive or aggressive. To use the OP's case as an example, if you said to the man in question: 'We've got a new rule, you can't hug the kids and you have to have at least two adults when you take the kids out anywhere', the only right response from him would be, 'Okay, that's fine'. Any attempt to bend the rules for 'special circumstances' or aggressive deflection - 'How DARE you imply...', etc, etc, is another red flag.
No one wants to think badly of people. No one wants to feel like the sort of person who's tarring all men with the paedo brush. But if historical cases have taught us anything it's that child sex abuse is so much more widespread and endemic than anyone could've ever feared possible. And it with all the revelations about Bennel and the Catholic church, as well as Savile, Cyril Smith, Haute de la Garenne, etc, it feels like we still may not have even scratched the surface.
So I would say, if your radar bleeps even very faintly, do not try and rationalise it away. The consequences are too dire. We must err on the side of caution, unfortunately. Because we must pay attention to the lessons we are learning from historical cases.
Finally, the last thing I would say is that women are just as capable of being child sex abusers. The behaviour described in the OP - particularly the unscheduled mystery trips alone with the children - would have me very concerned even if it it were a woman and not a man.
I completely understand that no one wants to live in a world of paranoia and distrust. But at the same time, I think it's necessary, unfortunately.
OP, your radar is bleeping. Don't ignore it.