It is likely to be either a hematoma (blood clot) or a hernia. It's possible
it could be a little wound infection, but those are usually quite painful,
red, and inflammed.

If it's a hematoma, it will resolve over the next couple of weeks. If it's
an infection, it will spontaneously drain soon. If it's a hernia, obviously
it won't resolve. The danger of such a hernia is that that lump you feel may
represent a loop or a knuckle of intestine entrapped in the port site, in
which case there is a potential for strangulation of that portion. That is a
potentially dangerous condition, although the symptoms of such a
strangulation aren't subtle - it would usually be quite painful. Usually, it
would be more likely that such a hernia would be some incarcerated
preperitoneal fat, or possibly some omentum, in which case there is no risk,
just an unsightly and possibly painful lump.

Your surgeon needs to get a look at this. He/she may recommend a period of
observation, or possibly re-exploring that little incision and fixing the
hernia if present.

HMc