re: Workshop fire -- averted . . . and a "whuf" question

I understand your concern but burns are fairly common and caused by a number of reasons: cutting too fast or slow,dull router bits,to heavy of a cut,type of wood being routed,or clogging of a groove or hitting metal,I’d say the biggest issue is vacuuming a newly router groove ,without that a fire is not likely unless you have flammable materials in close proximity.