I got two 2017-P cents in the change over the past week. Other cents minted in Philadelphia don't have a mint mark. I forgot all about the 225th anniversary thing in 2017 (attached link tells the story). Philadelphia Mint Quietly Releases 2017-P Lincoln Cent (coinweek.com)
Back on January 14th 2017 I created a thread on the P Mint Mark Cent. I believe I was the first person on CoinTalk to find it.. https://www.cointalk.com/threads/cent-2017-p-mint-mark-in-nyc.289476/