More like a physics or thermal dynamics thing. In this case the hoses to the can and the can itself act like a coil or "snake" on a moonshine still. As the vapors pass through, because they are cold, it creates condensate that falls out.Yes it is normal. You’re a little late to the party. If you do a search you’ll find lots of information about what folks are catching in their catch cans.
When it’s cold you will catch more vapor, it’s a chemistry thing?