While he may have cleared the air in one case, Boosie Badazz was dragged back into another legal mess, getting arrested by federal agents ... TMZ has learned.

A spokesperson for the San Diego County District Attorney's office tells us Boosie was in court Wednesday for an appearance in his ongoing gun case. The good news -- the case was dismissed. The bad news -- he still had another pending legal issue.

We're told Boosie was arrested by federal agents outside the courtroom as soon as his gun case hearing wrapped.

We don't currently know the circumstances that led up to the arrest.

As for the gun case ... reports say Boosie was involved in a traffic stop last month when officers discovered two handguns.