Potty Training... Take 3?

I think this is my third attempt at potty training. But this time I'm really serious about it (if I said I was serious in my other two tries, please disregard). And the good thing is that today we've actually had success! I started with Tommy yesterday after his nap because our morning was busy. He had 4 accidents between then and bedtime, and only one of them was on the couch, so that's a good thing. He still wouldn't tell me when he was wet (except when he went on the couch and then politely said "Mommy, I pottied on the couch"). He slept in a diaper last night and then when he woke up, I fed him breakfast and put him back in his underwear. He proceeded to have 4 more accidents and denied their existence (while standing in a puddle the size of Lake Michigan). Then all of a sudden, on the 5th pair of underwear (about 10:00 this morning), he crossed his legs, grabbed himself, and looked very panicked. We ran to the bathroom and he sat on his potty. And filled it. I couldn't have been more proud! He got to pick out an M&M (my bribe of choice this time), and put a sticker on his potty chart.

Then about 20 minutes later, he slipped off to the bathroom again and went potty in his potty seat (well, mostly) for the second time! I thought "Well, surely this potty training thing will be a breeze now!" I gave him lots of high 5's and more M&M's and stickers.

But then it happened. He suddenly decided he was done using the potty and didn't want to go anymore. We took a 20 minute trip to Coosh's to pick up some lunch and bring it home. I tried to get him to use the potty but he wouldn't. You're thinking "Is she nuts? Bringing him out of the house in underwear after only 2 successful potty visits?" Well, yes I am, but he didn't have the accident there. Thankfully he waited til we got home, but as I was pouring our drinks, I heard another pouring sound and looked up to see Tommy looking down and saying "Uh oh." When I tried to get him to the potty, he screamed and kept going. All over his shoes and socks. Lovely. So now he's in a diaper and is down for a nap. We'll try again when he wakes up.

So do you think we were 2 and done? Has he given up? Will there be a round 4 or will this be it?