Do "Blind Moments" Come in Threes?

Blind Moment of the week Number Two...
Yesterday morning I sent the dogs out the back door to have their first bathroom break of the day. Hermione, Nala and Roscoe came back quite quickly, but Otis was outside, barking his little head off. I lured him back inside-yes, I said "lured." Bribed would probably be the better word. I know, bad dog owner, but it was six in the morning and I really didn't want the neighbors to hate us. Bribing aside, when he was out barking, it sounded as though his voice was coming from farther back than usual.
I was a bit confused, but thought nothing of it. We have a six foot wooden fence surrounding our little backyard which made me believe there was no way anyone could escape. The landlord even said that her Britney never got out of that fence. So again, I thought everyone would be secured.
The morning progressed as normal: breakfast for me; coffee for me; school work for me...you get the point.
At about 9 AM I gathered the fuzzy troops and headed back downstairs for fuzzy breakfast. Everyone ate and I again sent them out to do their business. Otis was particularly excited to get outside, but I thought it was because he saw a squirrel up in the trees that was taunting him. While they were outside I unloaded the dish washer and started wiping the kitchen counters off, but as I started on the second counter something clicked in the back of my head.
I had never been able to unload the entire dish washer before without one of the dogs wanting in. The backyard is very small and they really don't like being out without me for very long. I had never managed to unload a dish washer and wipe down counters either. Slightly suspicious, I went to the back slider and called Nala.
Nothing.
I wasn't suspicious any longer.
If Nala was in that backyard she would have been right there.
No Nala and no scrambling paws in the dead leaves.
No dogs.
Trying not to panic, or at least trying not to sound like I was panicking, I called Nala a bit louder. Mr. K and I had interviewed a dog walker a few days before for times when we aren't able to walk the two little ones and I had given him my key. This meant that he also had my recall whistle. Upon this realization, the panic really started.
I called again, louder but still trying to sound happy and excited.
To my great relief I heard paws. Eight of them to be more accurate, but I needed sixteen paws.
Roscoe and Otis were the first to arrive. I was slightly surprised because it's usually the girls who come back the fastest.
Praise and scooting inside with a treat each followed.
I called Nala again and waited. It probably was only five seconds before I heard her thundering towards me, but it felt like an eternity. Little paws were there too. Another party, treats and inside. Hermione had been hot on Nala's heels. I'm assuming the two of them were off adventuring together. Wherever they all were, they must have been romping quite vigorously because all of them consumed their body weight in water.
To be honest, I felt more relief when Otis came back first. His recall is the least reliable without the whistle and he's the one people would steal. There is also a fairly steep incline down behind our place and I was worried he had tumbled down and wouldn't be able to climb back up, or worse, had been hurt.
So, how did they escape?
Turns out the back gate had blown open during the night. We had some wicked wind and I guess the gate couldn't withstand it. Unknowingly, I had whipped the back door open and sent my dogs out to pillage and plunder the forest behind our place.
Its it possible that Blind Moments come in threes?