I bottled an oatmeal stout recently and inadvertently added the amount of sugar I would use in 5 gallons even though I had about 4.25-4.5 gallons in the fermentor. Is this too much sugar, and will I need to worry about bottles exploding?
No...You simply carbed roughly to the level of beers with higher carbonataion. If you are carbing to style you are often using more or less sugar per batch of beer, usually somewhere around a half ounce more or less (approx) so it's not that different. Depending on what the beer is, it might even be the correct amount.