Congratulations on having undergone the tummy tuck operation. Although your plastic surgeon is your best resource, it is not unusual for patients (generally speaking) to have a small/moderate amount of drainage from around drain sites. Again, best to follow-up with your plastic surgeon to ensure adequate functioning of the drains and to ensure that you are doing well overall. Best wishes.
It is not uncommon to have some scant drainage through the drain sites. This should slow down significantly with time