|If this is your employee's biggest complaint, then he or she should be the one who is very thankful. With all of the possible problems on the job, your employee had to do some real digging to come up with this one.|
There are plenty of experts who indeed claim that it is all but impossible for a manager to give employees too much thanks, credit, or appreciation. Such feedback is often found to be motivational, uplifting, and quite satisfying.
At the same time, it is possible for excessive amounts of recognition to lose their meaning. If the employees are being constantly thanked for the most routine and mundane of behaviors, such appreciation gradually turns into background noise that most people ignore.
Since your employee did raise the issue with you, perhaps this is a good time to do a quick check to see if you might be giving them too much of a good thing. Since you want the recognition that you provide to mean something, perhaps it might help to turn it down a notch.
Either way, it is a very positive sign that your employee felt that he or she could be so open with you. Just to add a touch of irony to your managerial style, be sure to thank him or her for doing so.