That's not accurate.
The way SW works is, they have (at least for my market), about 6 different classes of fares. There (for the past 2 years, anyways) always been either a $49 or $59 one way internet fare from Providence to Orlando. Now, granted, these prices DO sell out, but the fare is simply listed as "unavailable", but DOES still show up on their website. When it gets closer to the flight date, those may not show up anymore.
However, the flights I'm referring to aren't until July, and last week, were listed on there as per usual under internet fare of $59. As of today, the internet fare is $109.
We all know SW has different pricing categories and that certain prices become unavailable, but again, they still show up online. Never, once, have I seen the internet fares for Providence to Orlando at $109. Never. Available or unavailable.