Tinder on hubs phone

You would know better than all of us..if you already feel something fishy going on then it could be possible that this is not work related. But if this is the only thing that has made you doubt him then I think you are overthinking. You need to have that much of trust and I don't think he is hiding it, if it is there in his phone and he knows you also use it then he is quite open about it. Also, I agree start having some discussions about each other's work, it's always good to know about new things.