In general when it comes to communication about such things as this we need the basics.
If it were me,I wouldn't worry too much about what he is thinking your reasoning is for asking him to call first. This is separation101 here. He has his place, you have yours. If it is me, I write him and say it as plain as day. Something like this:
Dear H, I noticed you were in the house today and to be honest, it makes me uncomfortable that I didn't know you were coming.
I would appreciate it if you would please let me know in advance if you will be in the house. It is not a problem for me for you to come over as long as I know about it.
Thanks,
W
As simple as that, no explanations are needed purple. He gets it believe me.....
