A good rule of thumb is that if a lot of people reply without making mention of previous threads, it is probably time for a new one, so you're fine.
If previous threads are linked to right away, you probably should have just "bumped" the old thread.
Usually, no one will complain if a year or more has passed. But unique non-road-related threads, like this one, tend to stay in people's memory for longer, too, so in this case a lot of users may still remember the previous discussion even after more time has passed.
No big deal either way; the mods will handle it as they see fit.