Yes you do. You need to determine if the amount you took from the IRA in 2018 satisfies the RMD.
https://www.bankrate.com/finance/money-guides/ira-minimum-distributions-table.aspx
If not, since 2018 is your first official RMD year, you can make up the difference by taking the rest by April 1, 2019. However, that additional amount (as well as the 2019 RMD that must be taken by 12/31/2019) goes on the 2019 tax return that you file in early 2020.