TSA has tightened up a lot in the last few months. A lot depends upon the airport you are flying out of these days. I know people named Michael and their ticket said Micheal and the TSA sent them back to have the ticket reissued. I would try and fix it in advance. As someone noted, if the ticket is all Delta metal and issued on DL ticket stock, they will not have a problem fixing. If there are code shares or partners involved, they will have a problem.
If you have been getting by with name not matching ID, I would start to fix that. Eventually, you will get someone who wants to follow the rules and it takes time to get the ticket fixed by airport personnel.