After my 99 sc 300 sits for a couple of days there is a little pool of oil that builds up on the outer lip of the vvt gear. Are these gears known to leak?

 

Yes, they can start leaking oil. I would recommend replacing it as a new one is only about $130 and oil on the timing belt is not a good thing. On my '98 SC300 the vvti gear started leaking so badly that I had oil seeping out around the timing belt cover. The oil leak also seemed to cause the vvti cam gear to no longer keep the timing correctly as my car started idling like a V8 with a huge cam, haha.