I personally think there isn't an issue. It truly depends are how you two are as people and how you work together. If you're happy together and you have plenty of things to relate to, then it's fine. Honestly the age gap thing slowly disappears as you get older, people stop caring once you've reached a certain age.
Heck I dated a guy who was 23 when I was 18, and we got on fine because our maturity levels were about the same. Now I am dating a guy 7 years older than me and we are really happy together.
It's all also in a matter of perspective. If people around you are not used to seeing their friends or family date with large age gaps, then they'll be uncomfortable with it, because they don't understand it.
Go with your gut and how you and your bf feel, not based on how others from the outside view your relationship.
Hope this helps... :)