I am 10 days post op. I feel my nipples are caved in. Is this normal? (photos)

Thanks for including photos--they are entirely diagnostic in this case--something we usually cannot say without examination in person! Your 10 day post-op timing of these photos also helps, as your implants are still high, and your own breast tissues "hang" from your newly-created submuscular breast mounds, giving you a mild "snoopy dog" or waterfall deformity. This is what is causing your areolas to be incompletely filled-out as well. As your implants drop into position and better fill your skin brassiere, your areolas will expand and look less "caved-in." I would not be so bold as to say "completely gone," but substantially better and entirely back to "normal." Honest! Best wishes! Dr. Tholen

Yes, something not correct. Best to be seen in follow up by your surgeon ASAP. Or seek second opinions in person. 

Your breast implants are still high and have not descended  down beneath your breast and nipple areola.  It is very early in your recovery and as the implant moves down hopefully it will attain a position beneath your areola and push the nipple areola  forward and if the implants do not to send properly you may however need a breast lift to properly position the nipple areola on top of the implant.