Cruise control question

I set my cruise on 55. It will drop 4 mph and then gain back to 55 over and over. Whats going on with that????

Mine does that too. It's annoying but I don't think there is anything to be done about it.

Its normal. Some newer cars are better at holding speed (especially if it has drive by wire). Most vehicles with cable or vacuum + cable operated cruise will do that. Its why using cruise usually gets alot worse gas mileage.