Is your agency website mobile friendly?
Another big reason to ensure your website is mobile friendly: Google has announced that its mobile search results will give priority to mobile-friendly sites. While this won't affect overall rankings on desktop machines, if your website is not mobile friendly, it may drop in the rankings when people search on mobile phones.
You can use Google's mobile-friendly test tool to see the results for your site.
What should you do if you don't pass the mobile friendly test? Don't panic, but do contact your web developer. It may be that it can be fixed with a few tweaks, but if your site is older, you may need to rebuild in a newer, mobile-friendly platform.
For more on the emergence of mobile devices, see Smart Insights report, Mobile Marketing Statistics 2015, which includes this graphic on the most popular devices used to search the Web.