T7 patch for bo3 flagged as malware after a couple months.

Hello, i downloaded the T7 patch to play zombies a couple months ago and up until yesterday it had never been flagged by Malwarebytes. Yesterday however when i ran the scan it flagged it as a trojan. The file it flagged was called T7PATCH.Dll . I just wanted to know if this is normal because i heard that the patch can be flagged, i just don't understand why it was randomly flagged now and not before. Also the exe is not being flagged, its the .dll file that is. Thank you for any assistance.