Did you brush paint or spray..? enamel or Acrylic?
anyhow....
I have had small runs ( sags) in the past when I have applied to much paint ... ( impatiently! )
I allowed it to harden fully--and then pared the run( s) flat with a very sharp blade
one time I simply varnished and al was well
teh other time aftre paring I gently sanded locally around the pared runs and surronding area na d gave the entire area a thin light coat of paint to blend it al
good luck
Jim Baumann