If the hits are only at your remote server, you probably have little reason to be concerned about your own machine being infected because of them, particularly since you've gotten a clean reading from a current AV. Obviously you do want to keep your own AV current, and use it full time.
Your best contact for an explanation would be with the host at your server. While you could attempt to ask sagonet.com about this, you're not really their customer so your chances of getting them to even investigate are probably pretty slim. A query from your server's webmeister would be more likely to get a response, or he/she may have an explanation for you without contacting them.
If your service is current with bug patches and runs AV to protect itself, it's possible that these "zero bandwidth" hits are something your service is aware of and is rejecting because of viral content or "suspicious origin." There are a number of "searchers" that hit on web connections just looking for open ports. The contact can be very brief, and if they don't find one they move on. Since they often "generate" URLs pretty much at random, you can get quite a few repeated hits from one of them if one is "working" a range of addresses that includes yours. There have been recent reports of increased traffic of this kind directed specifically at servers, but operators who keep their machines up to date are seldom affected by them - except for the nuisance excess traffic.
Unless you can identify some "damage" that needs repair, complaining to the service that hosts an "unknown.something" is a little like emailing a spammer to ask them to remove your name. Not likely to be productive.