Since starting neurontin (gabapentin) 300mg twice daily 3 days ago, i've had these weird vivid dreams and teeth clenching. are these normal side effects?

Not rare: side effects. Mostly they tend to go away. They don't sound all that bad and if you get significant benefit from neurontin (gabapentin) (which is overall a VERY safe drug) then, it's probably worth it.

It is normal: Nerontin differs from most other anticonvulsants because it has minimal drug interaction potential and is not metabolized in humans. These side effects may go away after a period of time, as your body adjusts. If concerned ask your doctor for more information. Take care.