It is time for the next GRIN hardfork that is scheduled to happen tomorrow, January 16th on block 524160. The fork includes an algorithm change of the Cuckarood29 to the new Cuckaroom29, the other algorithm that Grin uses C31 will not be affected by the fork. So if you want to continue mining Grin after the fork with C29 you will need to update your mining software with support for the new Cuckaroom29 algorithm.
AMD GPU miners might want to check out the latest lolMiner 0.9.5.1 that has introduced support for Cuckaroom29 on AMD GPUs with 8GB video memory. Nvidia GPU miners might want to check out the latest GMiner 1.93 that also brought support for Cuckaroom29, but the developer fee is 3% for that algorithm at the moment. The latest GMiner also brings support for Cuckarood29v algorithm (MoneroV), though the dev fee there is a hefty 10%.