That reveals the care, and probably good technique, of a craftsman.
If you take the time to do this while working under professional conditions (on the clock), more the better with "hats off" to whomever is paying you for allowing you the time to care.
I suspect that many plumbers already have leather gloves with them and, after sweating the joint, simply STUB OUT any little fire they MAY have started. Most such locations are usually little more than a little, black soot on the wooden member.
As the utility worker denizen of many a crawl space, I cannot tell you the number of "torched", wooden members I have seen adjoining a plumbing joint. I do NOT, however, recall anything particularly bad. It's more unsightly than anything else, really - as long as they extinguish whatever they may have inadvertently ignited.
I assume the code requires protection of adjoining members when soldering a plumbing joint.