I have a hard time recognizing my depression until it gets pretty bad because a) I've struggled with it for so long, since I was very young, I have a hard time differentiating it from "normal" and b) my biggest depressive symptom is just being really, really tired. Like exhausted despite ten hours of sleep the last five nights tired. Which can be caused by a lot of things, so often I let it go for several months (oh I just need to take more b-vitamins! or catch up on sleep! or do some yoga! or work out more! coffee coffee coffee LOL) before I realize whoa I don't want to get out of bed and haven't for a couple of weeks now...

so no, I don't think it's always obvious or noticeable, especially if you have struggled with it for a long time.