Dennis Rodman's a member of the new mile high club — the one composed of people who allegedly refuse to wear a face mask on commercial flights — and cops were waiting for him when he landed.

Rodman flew from L.A. to Ft. Lauderdale Monday morning, and was allegedly told several times to put his mask back on by JetBlue staffers. Law enforcement sources tell us Rodman would first oblige, but then pull the mask down, citing he was having trouble breathing.

That's a big no-no…