i have had that happen before with a common pleco i had years ago. They just need to go terrestrial it seems. when my water gets low (when i am cleaning the tank) my current plecos sometimes stay on the wood that is exposed to the air for about 1 - 2 minutes before they "decide" to go back to the water.
Lunchbox ... "i'm a man, but i can change, if i have to, i guess"
Tankless ... for now ... until i find what i really want (and what the wife lets me get!)