I am pleased this issue has been raised thanks, as I have found quite a few errors in my ancestry, names birth dates  ages in censuses etc.
I have not informed ancestry , but if I know the information is  one hundred percent incorrect and some one else as the same person in their tree . I will contact them .and   mention it,
a couple of members have checked again and put the correction in their tree.
it can be confusing to have incorrect information, we found some one with my grandmothers name and birth place but the age on  her birth certificate  and her marriage certificate did not match, 
seems she lied to make herself appear younger when she married so It is alwys worth checking.