Spirograph

I'm in Phoenix, so it's around 115 degrees F mid-day right now. I have a new '04 6-speed (about 3k on it since I bought it w/ 36k). I have a 30 mile commute and it's consistently had the fans stay on after parking at work. Well, the past couple of days, I haven't heard that. My wife is out of town so I can't have her check if the fans come on after idling for a couple of minutes at 2500. I think it must be related to changes I've made the past week. I popped the air filter box out to remove the baffles, I swapped the crap battery for a yellow top, and I changed the who knows how old 5w20 oil out for 10w40. Is it possible that the oil weight change was so significant that the engine runs cool enough at 30 miles of constant 75mph 6th gear in triple digits, that the fans don't need to turn on? Seems unlikely, and it also doesn't have the fans on after driving around for a couple of miles at high rpm mid-day. Maybe I disconnected the plug to the fans by accident when I was working on the intake box? Any other ideas? I looked at the fuse/relay chart and it shows 3 different relays for fans (and another fan elsewhere, I think the air blower fan).