That's pretty normal for where you are in your quit. This is the way I saw it when I was going through some weird stuff around that stage in my quit. You fight like hell for the 1st month - month & a half. Things start to settle down then but you are still super focused daily on your quit. It's top of mind all the time. You start getting to three months - hey! Everything's different now. You're sort of king of getting comfortable with things now and the newness of the early quit has long since gone. Your mind isn't super focused on the quit thing all the time now. That's when your brain's autopilot kicks in - like your trip to the garage thing and those random thoughts like, hey I should head out for a smoke now, when something is happening that may have brought you to a smoke before.
It's an easier time in some ways but it can also be a more dangerous time. You gotta just do what you're doing now. Realize what's going on and that it's just not what you do anymore - smoking that is I gotta say, it takes a full year at least and probably even more before those random thoughts stop coming with frequency. It just takes our brains soooo long to readjust. It's not hard all that time, you just need to stay on guard and not act on any thoughts you might have about smoking.