Houdini FBT--keep those lids on tight!

I have a 55 G tank with 7 FBT's, 60% water & 40% land. One of my toads, whom I call Motley, is much more inquisitive & active than the others--a real personality. If I change anything around, or put in a new plant he is right there investigating. A while back I posted a pic of him when he had scaled all the way up the glass to the top, (18"!) so I've always been careful about keeping the tank secure; I have magnets siliconed to each corner, so the top is secure and I put a book on it also.

But tonight, I had the top off and was doing some of the things I regularly do--changing out some water, misting, fussing with some of the plants. I noticed that Motley is really looking good--I've been feeding the crickets Fluker's orange cubes and I noticed how much brighter his abdomen is. He was in the water and I stepped away for a couple of minutes and turned back just in time to see Motley flying out of the tank!! Couldn't believe my eyes, but there he was sitting on my bed, checking everything out. Needless to say, I put him back in the tank & secured the lid.

But it leaves me wondering about a couple things:

First, there has been a couple of times when I've had the top off--it's a regular top with metal edges and screening--and it seemed to me that Motley was looking up, checking it out--maybe thinking about making a break? But I thought I was just imaging it, as it's a long way up and their eyesight isn't all that good--based on how many crickets they miss. But I maybe I was wrong about that--did he really know that the lid was off & was he planning an escape?! Are their little frog minds that complex?

I also have put some pictures by one side of the tank, one is of the ocean with a lot of large rocks, and he sits and looks at it. Now, I'm concerned, because he is such a feisty little guy, could he be feeling 'trapped' in this tank, and really trying to escape? Does he need more space to explore? Am I turning into an old, weird frog person?