Well it could be. Do you know? When was the last time you checked the visitor statistics?
Search engines, and especially Google, make changes to their ranking algorithms on a regular basis so, if you checked you site 6 months ago and expect things to be the same today, you could be in for a shock.
Google Analytics is free and provides a wealth of data about the performance of your site. Together with Google Webmaster Tools, which are also free, you have enough instrumentation at your fingertips to know how your site is performing and why. Use them.
You get what you inspect, not what you expect.