When I sold my L, it was in this range. I bought it for certain purposes for my land that a smaller tractor couldn't handle. Once done with those jobs, I sold it for what I bought it for new and moved on to the smaller machine I need for general chores and maintenance. Like the OP, the buyer was a little suspicious since it was so clean. Garage kept and virtually spotless aside from some wear and tear in the bucket.
I'd been quoted $6k minimum by a few guys for doing the work (grading, clearing, rock relocation, tree removal) I bought the bigger tractor for, so in my free time, I'd do a little here and there where I could, and saved the $6k since the tractor was virtually free to own during that time. Sure, there was a little hassle and I had to spend an hour or two to sell the tractor, but it was well worth having the larger tractor for that stuff.