Airlines drop prices all the time. In fact, there’s an entire message board here on FlyerTalk just for Premium Fare Deals — good prices on PE/J/F inventory.

Basically, airlines sell their inventory based upon a projected demand curve. This far in advance, they’re not expecting to have sold many seats yet, so they’ll often keep fares high. If they sell a few high-priced fares, great! If not, they have plenty of time to offer discounts. (Heck, 10 months in advance, United’s schedule is basically notional anyway; they tend to firm it up about 90 days prior to departure).

Assuming they don’t actually sell a bunch of those high priced seats, they’ll start to discount them once their model suggests that they need to stimulate some demand. As suggested, in most cases, I don’t even look for domestic flights until about three months prior to departure. The best fares are usually available sometime between three months and three weeks before travel. If you specifically need to travel on October 1, I would set a price alert on Google Flights, and then I wouldn’t worry about it until June or later.