On my front facing camera as well. Bought at Verizon, they told me i have to go through Samsung. After a live chat, email and a call finally got them to issue a service ticket. Unfortunately my phone has a crack in it, so they may try and pull a warranty invalid on me i (never been dropped, my guess is from bending in my pocket, yes i have a case).
In the email they said it wasn't a known issue then link me to a troubleshooting guide for the issue... This site wont let me post links as i just registered just add the http deal to these
support-us.samsung.com/cyber/popup/iframe/pop_troubleshooting_fr.jsp?idx=527950&modelname=SM-G900V&modelcode=SM-G900VZWAVZW&session_id=V2nLFkQNLYDvSyXQPZQvSLkRpLpkpnJbBCXnGL9ZjK2TPbwXBTp6%21-1610719882%211920440247%211430136648644&from_osc=&homeid=29189
Researching the issue further not only brought me to this forum but it shows me that this has been happening since the S3. It's a camera sensor defect.
thedroidguy.com/2014/07/fix-samsung-galaxy-s3-common-problems-errors-part-28-95444#D2obCzwEuXx8p4OG.97
forums.androidcentral.com/samsung-galaxy-s5/398154-galaxy-s5-camera-issues-pic-attached.html
androidforums.com/threads/blue-dots-stains-on-camera.739826/
community.koodomobile.com/koodo/topics/blue_dots_on_camera_screen_pictures_on_my_brand_new_samsung_siii
I really hope they just send me a new phone and don't give me any crap over the crack. I'll keep you posted on the results, they said it will take 9-11 days.