Is the index 1 in the substituent name "1-methylethyl" a redundant index?
I'd not subtract a point for your "mistake," because there is no point to prove you are wrong. However, suppose the group is different than methyl. Then the position matter at that point. Say its bromo-group. So, 1-bromoethyl- and 2-bromoethyl- are two different things. That's why that rule is for. Can't give any favors just for methyl! :-)