Oh Gosh. That may not be a good sign.
that VSWR is *not* the "goodness factor" that says
it is radiating better. It actually tells you that
less is being reflected back down the feed.
A very lossy antenna, say one that has a dummy
load connected across it, or maybe laying on the
ground in a pile of wet grass, might only be warming
up the leaves, and has an excellent VSWR!
Try an unpainted in a test. Then paint it, but
touch nothing else.
Actually, I am thinking that
the paint will not make any difference. There may
be other factors that made the VSWR measure better
second time around.