My advice doesn't end with Coinbase only though, stop leaving your coins on any centralised exchanges in general.
It's completely wrong leave funds for long time on exchange if not using them to trade, for me I would prefer when trading then moved fund back to exchange to execute that but if not in used there is needs to pull them off from centralized exchange. I goes by the popular phrase 'not your key, not your coin' and there is every chance of losing ones asset.