Ah, I was curious about where I read that and found it in the Companion Pass program terms on the SW website (emphasis mine):
"The Member and the Companion must check in together and, if asked, present the Companion Pass card at the Southwest Ticket Counter, Skycap podium, or Departure Gate in order for the Companion to travel. "
I brought it with us because at that point what was one more card to carry?
2) I haven't had a $59 fare in a while. I miss them. Last great deal was $44 PHL-MCO in Dec 2015, I think we booked that in Nov. (It was an unplanned last minute trip to see the last Holiday Lights show once we saw how cheap flights were).
For us the $59 fares were short hop, non-stops. I'm not sure where they are now but not out of PHL that I've seen.
3) Deals pop up at various times. If you're flying during a peak period or peak day/time then it's usually better to book it earlier rather than later. Weekends are usually more pricey than Tue-Thu, so when I booked our Seattle flight for Friday I grabbed it on schedule open and it never went below that price. I think the 737Max grounding has affected the pricing since there's the same (or more) demand for less seats