Killed it on my tempo run

I decided to do my 5-mile tempo run (middle 3 miles @ 8:23 pace) today. I walked each dog around the 3/4-mile neighborhood loop (and racked up 2.25 miles) and finally got out on the road just before noon. It was pretty warm for November (68 degrees) and slightly breezy. My first mile was pretty good for warm-up (9:19). I kicked it into high gear, and for some reason I did the math wrong in my head at the 2-mile marker and I thought I split just under 8:40. So based on that cruddy math, I thought my 3rd mile was just under 9 minutes and my 4th mile was around 9:20. I was getting frustrated, because I worked hard. I was wondering how on earth I would hold 9:09 pace for 26.2 miles. I blamed it on everything - the weather, my tiredness, walking the dogs beforehand, etc. Then as I was warming down, I realized I'd finish in 42 minutes and change. That's when I redid the math and realized that my splits must have been much faster. I couldn't wait to go home and go through the Garmin history. I busted through the door and exclaimed to my husband, "9:19, 7:39, 7:57, 8:16, 9:21!!!" I was so excited! I can't remember ever breaking 8-minute mile pace on a run (since maybe middle school??). I took my shoes off and iced my feet in the pool while I updated my Facebook status (such a dork, I know this). HOW FRIGGGGGGGIN EXCITING!!!