You don't know what you don't know. That sounds obvious but it's not, really. Speculating will get you nowhere. having a plan will.
Call it the "Courtesy Blowout Call"
"John, it was a pleasure connecting with you and helping out with your lawn a few weeks ago. I would like to become your regular lawn service if that is something you would be interested in. I left you a few messages previously and going forward I don't want to be a pest. If you decide that regular lawn mowings/sevice would be something you want to have done, please call me at XXX-XXX-XXXX. If I don't hear from you I will assume you have gone in a different direction. Thanks again for your interest, I hope to hear from you soon."
Done. Don't think about it, or worry about it. You did nothing wrong. A certain % will do this no matter what you do, all you need is a process that you follow that will always get you where you want to go.
Letting him go will allow you to focus on other new opportunities. If he calls back terrific, you stand your ground and tell him you are looking for regular cutting jobs. You assume too much, even with experience, about what an individual is thinking. Don't assume anything, just have a process that treats everyone fairly, including yourself.