They're probably a couple.
"Honey, I know the place where I found some yummy ramshorns was around here somewhere."
"Why don't you stop and ask a Tetra for directions? This doesn't look right- there isn't even any water up here."
"I don't need directions- honestly it's here somewhere."
Seriously though, check your water parameters- snails leaving the water when they're not normally doing that can be a sign you need a water change... there again some snails regulary leave the water- I've not kept assassins so I don't know if they will.
Most snails can live out of water for a time- they won't die unless they escape the tank completely and can't find their way back...