I am very concerned with any 'strange' sign in my mbp, because in the past, in other mac machines, I had some failures, and from this time then, I watch carefully for any change in the 'behavior' of my machine. My mbp (late '13-yosemite-ssd), was booting in about 15 seconds. All the time, as far as I can remember. Now it does not. It takes about 30 seconds. And I can't tell that I installed anything 'strange' the last days. I run 'etrecheck', no problems mentioned there. A check in login items, did not showed me anything new. Can you suggest if there is anything I check about this delay? If there is any problem in the way and I could avoid it, it would be perfect.