It is a good thing. It is awesome, actually.

The customers were not complaining, but proposing positive feedback on how to improve your product. You could gather the information, do a detailed analysis, and present them to the upper management, in a positive way. So it is an oppurtunity to show them that you are doing, or trying your best to do, a good job.

Also, keep a close biz relationship with the customer. It may help you in the future.