Sounds like you were not properly "served". Technically the ticket is (in most states, anyway) a notice to appear in court. The officer handing it to you is considered "proper service". Getting you to sign it just helps him prove that he served you properly (but probably isn't required of him). Improper service is grounds to get the warrant revoked, but that's been done.

It's not clear that, even now, you've been properly served. Going to the court and getting a copy of the ticket probably counts. If you find that getting a copy of the ticket directly from the court does not constitute proper service (very unlikely, though perhaps the fact that it's not signed by any human is a problem?), you could just wait for them to serve you, but this seems most likely to just get another warrant issued, get you in even more trouble, and not produce the effect you want.

Going to court and arguing that you weren't properly served even by the court office (assuming it's true, that is) seems like an iffy argument since, like, you're standing there in court, right? Even if you win that argument, Georgia has 2 years (I think) to serve you and bring you to trial. If you make 'em do that, they might take it personal!

Why not focus on the underlying infraction, rather than try to beat it on a technicality that doesn't look like it'll stand up no matter what in Georgia?

(Here in California it might actually work to argue improper service, then argue the 45-day limit for a "speedy trial" had elapsed. Georgia has 2 years, so you're probably stuck.)