I was certified in 2005 and the Instructer said flat out " if you do not feel like diving Do not, You feel something is wrong during the dive abort"
We were told not to pressure any one to dive and as As a Dive master I have worked with some people who had to abort the dive for various reasons.
Some of the reasons:
Equilization trouble
Panic
Unsure of suroundings
Intimidated by drop off to deeper water on one side or the other
Imtimidated by aquatic life
All of these divers were wise in aborting the dive and will be safer divers in the future in my opion.