Alright, so, here is what happened.
Last sunday (not this previous one, but the one before), I decided to do an oil change on my FiST. Everything went fine, except this time instead of using the FoMoCo oil filter I used a K&N one, I made sure that they were the same size and everything, and went ahead and did my thing.
Here is the thing though, when I got home Monday afternoon, I noticed some oil on the driveway, not a huge amount, but enough for me to go, "what in the shit?" Because there was also a dotted trail of oil from where I back out to leave in the morning.
So, I put it up on ramps, and make sure that the filter and my drain plug is tight, I saw there was some oil splashed onto the pan, and the only place it could of came from was the oil filter. I had put in what the car calls for. 4.73 quarts. I honestly didn't know what to think, so I checked the oil dip stick, it was fine. And told myself if there is oil again tomorrow I'm going to change it, and parked in a different spot so as to see exactly how much oil will leak out.
I come home Tuesday night, and there is another patch of oil on my driveway. It looked to me, to be about the amount of oil that sits in the oil filter. So I said screw that, changed my oil again, and used the filter that Ford calls for, and I haven't had a leak since.
Before I put the new filter in, I held both filters and compared them side by side, to see if there was any difference, and there was:
The K&N in question (K&N HP-1002)
The Ford filter.
If you look at both of those filters, at first it doesn't seem like there is a huge difference. But I was looking, and I saw that the lip of the K&N filter, on mine at least (sorry no picture available for mine), was it looked to be an additional piece, maybe aluminum or something, that was put on there. But for the Ford one, it looks like the lip is a part of the oil filter itself.
It didn't look defective or anything, just that the lip was not a part of the oil filter body like the Ford one's was.
So, my only theory is, since I was ONLY leaking oil at night (I checked throughout the day on Tuesday) once I parked for the night, was that the lip on the K&N filter was contracting once it cooled down for good, thus squeezing the seal and breaking it a bit, allowing the oil in the filter to seep out slowly. It also doesn't help that the filters go on horizontally on these Fiesta's, but whatever.
TL:DR, K&N filter leaked, the stock Ford one doesn't, did I get a defective filter, or is there more to it?