You only need a small amount of solder on the tip of the
plug, so unless you applied a large amount, with a very high tip temperature and had the
plug vertical when you did this, it is unlikely that the solder has moved through the tip to the braid or the body.
In my experience, the two most common causes of shorts on a PL259 plug are:
1. too much heat being applied to the braid. This results in the insulating material around the
core wire melting and exposing it to the braid; and
2. stripping too much of the
core wire
insulation and having a stray braid thread touch it when you push it into the plug.
As a final note, make absolutely sure that the
antenna is not connected when you are testing for a short as some antennas will show as a short on a multimeter because they have a matching coil.