Will I gain weight or fat?

If you consume more calories than you burn, yes, you'll probably witness the weight gain on a scale within a week or so. However, I'm betting it won't be that much. It you're still within your goal range, don't fret, and if it is necessary, just eat a few calories less than usual in the next couple days/weeks.

You sound overly hung up about this. The labeling of eating a little more food as "bad" is extremely unhealthy thinking.

We don't have enough information to know whether the extra food was enough to take you above or beyond maintenance. Even if it is beyond, unless you somehow crammed in 4000 extra calories, which I doubt, it's unlikely that you will notice any permanent increase on the scales, in a week or two.