Oh the horror, what happened to my 340...

Well that's great. I am super glad it was so simple. Did you put blue locktite on the bolts and torque them to spec?

Glad it wasn’t anything serious.
Been following this and wanted to tell you that it’s real common to drive the car with no noises from the converter bolts and then they make noises the next time you drive.
Heat swelling makes them a little tighter and next time it’s started everything is cold and loose because the metals contracted.
Seen this more than a couple of times.