Had my alignment done today. I'm used to seeing a split left and right but I just did my radius rod bushings and my caster is nearly even.

2.9 left
3.0 right

Question, is this ok? As far as driving it drives very straight but seems to have a vibe in certain conditions. Not sure if it has to do with the caster though.

 

Caster can be slightly different to accommodate the crown of the road.

Vibrations are usually not due to suspension alignment, but because tires are out of balance, or worn unevenly.

Here's an excellent video explaining alignment:

 

Yes, your caster it's ok. The caster is not adjustable and should be the same or close to it.