Nah, moe was extremely noticeable when it happened. So much so that when it became a recognized thing there were tons of discussions about what the word meant and what it defined in both the Japanese internet and the rest of the world.

There was always fan service in Japanese media. However after the bubble burst fan service kind of stuff became the only economically viable way to support the continued existence of the media outside of fringe cases with genuinely talented authors and artists.