5 days post FUE op, I have scabs and crust. Should I be rubbing it gently while washing it or will it fall off on its own?

It is best to contact your doctor about post operative care and instructions since each doctor has a different regimen.  You should go back to see your doctor so your doctor can help you with the scabbing,

At this point you can be a little more liberal about massaging the area in order to expedite removal of the crust.Please check with your surgeon regarding post op care.

This is something that should have been fully discussed with your doctor. At this point you should be gently rubbing to help loosen/remove the scabs. For most patients they should be scab-free within 7-10 days after their procedure, 14 days max.

An FUE is treated just like a regular hair transplant with regard to the recipient area, but the donor area has open wounds which require daily washing with soap and water. Within 3 days of surgery, you can resume full activities, heavy exercises if you wish. The recipient area requires daily washes as well to keep the recipient area free of crusts. I generally recommend the use of a sponge and supply my  patient with a surgical sponge to fill with soapy water and press on the recipient area daily. By repeating this daily, all crusts can be washed off without any fear of losing grafts. IF any crust are present, use a Q tip and dip it into soapy water, and roll it on the crusts and that will lift them off without dislodging them, but never rub them, just roll the Q tip on the recipient crust. I like to see no evidence of any crusting in the recipient area and the crusts from the donor area gone in 7-10 days with daily washing