be cautious. i have done it several times but that was KE connecting on KE and overnight in ICN. DL also did it for me connecting on MU before. they didn't recommend it in the beginning, but i insisted my connection was only 2 hours. my suggestion is that if MU is willing to check all the way through, go to the transfer desk when you get to ICN. it is located next to the transit hotel anyway and let them know about your bags. do it again before you before for the detroit flight the next day just to make sure. ICN is pretty good with customer service anyway. there is NOT a whole lot to do inside the airport. i normally just get a transit hotel 10 minutes away. good luck!