Possibly the low winter humidity. My printer room only 400 miles to the south of you is down to about 25% today, versus more like 40%+ for most of the year. My 8300 doesn't seem to care about humidity as far as canvas goes, which is all I print now. I recall a couple swipes on 210 GSM Rag Photographique, so maybe it's a chronic thing. Nothin' worse than springy paper.
Worst case is you can decurl roll paper and feed it as sheets. Or decurl uncut roll paper on a very clean table in front of the printer, then roll it back in for immediate printing. No fun at all.
The 8300 has a tendency to minutely raise the media under the heads as the leading edge goes over that little ramp at the point where the media emerges from under the cover. If you're getting swipes about 6 inches past the leading edge, that's what's happening. Only happens with viciously stiff and curly media. Easiest fix is to feed the curly leading edge of the media past the ramp by about an inch before starting. Alternate solution, before printing feed a couple inches of media, open the cover, and with your fingers decurl the leading edge slightly.
Also, have you been cleaning your Blue Switches? Old toothbrush, stiff art brushes, etc. Very messy, don't contaminate the rollers. There seems to be an internal sensor for checking the vacuum, I get nagging error messages about dirty Blue Switches a few times a year and cleaning makes them go away. So if you're not getting such messages your vacuum may be within tolerance.