No brainer, yes. Always be on the lookout for what the job market has to offer. The bottom line, employers will drop you if they feel they can get a better deal

No brainer, yes. Always be on the lookout for what the job market has to offer. The bottom line, employers will drop you if they feel they can get a better deal with another employee. You should have the same mindset. If you find something better you should take it. As far as learning goes, don't expect to be assigned a mentor or to find a mentor at work. Most startups just don't have the ability to provide one. There are just too many things that need to be accomplished for it to stay alive so they won't be focusing on mentoring developers. Plus highly experienced developers are looking to get paid for their abilities so they are job hoppers looking for the best job for them so don't expect them to stay too long unless your startup is exceptional. Your best bet is to learn by doing, move on to another startup and learn from the experience. Also, map out your career. Where do you want to be in 5,10,15 and 20 years? I can almost guarantee you won't be a developer in 15 years, and I don't even know you,so plan for that.