first, what's your device model? and is the device up to date?
second, do you have some other app running in the background?
you could try to see what app is hogging the mic, the message itself I don't think is an issue... rather the fact that something else that you are not aware of is using the mic seems to be the issue.
lastly, If you don't want to bother tracking it down. you can submit an issue report on Samsung Members app after trying to wake up the assistant again. It'll collect log of what the device was doing at the time and hopefully find what was using the mic at that moment.