Just My Luck Today, Right?

So yeah, I had the weirdest morning today. Woke up late because my alarm went off at some dumb hour and I hit snooze like 30 times. And when I finally rolled out of bed, there was this weird fog in my brain from lack of sleep, you know? So not the best start to a day, but that's life, right? Anyway, so I'm in the shower, trying to get all clean and awake for work, and suddenly...I have this urge. It wasn't really planned or anything, just kind of hit me out of nowhere. So there I am, soap sliding down my chest and water pounding on my back, hand sneaking under the curtain, fingers closing around myself. Felt so good to get rid of that fog. And then it got weird. Don't know if it was from the hot water or what, but I suddenly had this fantasy about this girl I sort of know, kind of like a friend with benefits? We've done things before and all. Anyway, next thing I knew, my hand is moving faster, eyes closing tight as I imagine her naked body in front of me. It's funny, because she's actually not my type at all. Blonde hair instead of dark brown, much smaller boobs than I usually go for, that kind of thing. But there was something about her soft voice and her way of touching me that just got under my skin this morning. Anyway, back to real life after the shower, grabbed a coffee on the way in and tried not to think too hard about it all day. Work wasn't bad though, met up with some friends for drinks later when I got off, which was nice. Got home around 10 or so, tired but feeling better. So now here I am, sitting on my couch in the dark, and...I'm getting that same urge again. Only this time it's not just a little quickie in the shower, it's like every nerve ending in me is tingling for her, even though we haven't talked in ages. Wonder what she'd think about all of this if I actually told her? So here’s my question: Is this normal? It’s kind of embarrassing to admit, but it feels so out of the blue and strong that I’m starting to wonder if something's up with me. Or am I just being paranoid?