Just something I always do if I am paying cash to buy something from an individual who doesn’t really know me. It’s always an awkward moment when you are the seller and you get handed a bunch of bills. While it would be wise to count them immediately, it would look like a lack of trust on your part. So to diffuse the situation(as the buyer), I always hand them the money and say, “Better count that to make sure”. That way they can do it or not, but if they do want to, it looks like they are doing what I suggested and they don’t have to worry about offending me.