To be honest, Verizon has a very little role in porting out process so you will need to contact Straight Talk's LNP support team.
In the mean time, even after a port out is completed, your phone can be active for a few days with the old carrier.
Give it a day or two. If it has not successfully been done by then, I'd start asking questions.
like most things with straight talk, their service is slower
give it 3-5 days