Noisy Sony Dvd Drive

My Sony DVD drive was purchased 18 months ago. In the last few days it has started making a lot of noise (when READING a disk) even though it actually reads the contents without any problem. It does not make this noise during disk WRITES. It is even noisy when reading disks (both CD and DVD) which have been burnt by the same drive. I have noticed this high speed spinning noise in the past with other drives when they have difficulty ready a scratched or dirty disk but the DVD drive is noisy even when reading brand new disks.
Does this sound like it is the beginning of the end of this drive?
Why would it be making so much noise when reading?
Thanks in advance
John

 

Possible it is running fast because the DVD lens is dirty, needs cleaning.