What you are experiencing is quite common. Most seasoned builders try harder to push and pull the alignment a little more before they tape. Even the best builders, often cannot get a perfect alignment simply because the pieces get distorted as the interior epoxy and glass shrink - which doesn't happen evenly. Don't worry, sand it flush and tape the outside seam. Wet it out first with some alcohol to make sure your feathered glass edges are wetting out OK. If not, sand any glass areas with a super fine grit paper - that usually does the trick.