1. Lots of flights are overbooked. Very, very few are oversold.
2. If your flight is oversold in F and you are an unlucky selectee for DG, make certain that the GA is using UA's software algorithm for the DG order. As a paid F 1K, you should be last to be down-graded other than a paid F GS. The DG order is essentially the reverse of the UG order with paid F at the very end. Please verify that you really are on a paid F fare, not some -UP fare, it really matters.
3. If you are bumped to Y, you are due a refund of the fare difference between F and the Y fare at the time of the bump (yes, it's unfair but it's been raised to DOT time and again).
4. UA as a service recovery matter will also provide a cert for $1,000 on a flight of that length. You might want to consider that.
5. Lastly, UA will rebook you onto other F services, but they won't be convenient and you have a short trip.