I'd tell him that it was perhaps a case in days when he was go-go boy but world moved on. That should be keeping him at bay as it's none of his business.
Your mistake is wrong tipping technique, I always tuck tip in their underwear and if they wear none , in their sock so amount it's surprise even for them.
Only case when you may see how much I tipped is fuck show boys who usually keep tips in their mouth for all to see.
I don't think boys will expect the same from everybody, they may HOPE that next time when that particular client will show up, tip will be the same but if it won't, they still have good sense of what windfall is opposite to regular rates.