I really think it is.. it's something I noticed long before I had any hair issues, lots of kids have hair in these areas and it always seems to have gone in adults, my sister is 22 and still has really prominent .. I dont know what you'll call them, she stilll has mousey hair there like kids do, most people have really fine hair there or no hair at all when they become adults, I really think it's a non issue, of course it's up to you at the end of the day.
Re: hairline. I have diffuse loss all over the top but my hairlines still the same, when I started obsessing over my hair I was sure mine had changed from a straight hairline to a curved one.. but looking at photos where you could see me top-down it was always like this... my hairline looks straight if you look at me head on, from the top it's U shaped.. because my head is also curved of course..
I think anyone with a true straight hairline would be unusual (in the nicest way possible) =], almost everyone has a curved one, of course I'm sure you know better, but I really believed I'd receded a lot before I got a bit rational about it. I have a perfectly normal hairline. I think you do too.