Are the NB rocker panels 'sealed'?

[03TDICommuter]

Finally got the time to change the radiator out on my '01 Beetle. While the fenders and liner were out, I cleaned all the built up dirt. The rocker panels have an intentional 'port' on the lower forward side - both of mine were plugged but now I think that was intentional. I stuck a screwdriver into the hole, removed dirt but it also looked like white caulk. Now I have an opening from the rocker panel to the environement and think I should seal it back up.

Does anyone know if that port is supposed to be sealed shut? I'm thinking it was there for manufaturing and then later sealed.

Thanks