Neither of those are things that you should feel bad for noticing and being bothered by. They are genuine "but"s to being able to enjoy the book. I do hate, though, when I notice something like that and it kind of ruins a overall enjoyable book.

Dear Lois Lowry,
I'm afraid such glitches do bother me quite a lot. I enjoy doing research so much, that I'm always annoyed when it seems that an author didn't take the time to double-check facts. Perhaps one might not think to check whether pantyhose was available in 1950, but...why not? Especially with a historical story, a writer should make certain she or he understands the period very well, in detail. How can you create a true snapshot of a time if you aren't so thorough? I'm afraid there've been too many times when I've read stories, especially those set during my lifetime, when I've been halted because something wasn't right which could have been checked, such as the date of the moon launch or whether Captain Crunch was in stores yet. To not clean up these glitches is to misrepresent the period the author is writing about.
I used to blog, and I once did a post on this subject...actually, it's a rant (you are warned):
http://moiramanion.blogspot.com/2010/06/quick-comment-facts-is-facts.html">http://moiramanion.blogspot.com/2010/06/quick-comment-facts-is-facts.html" rel="nofollow">http://moiramanion.blogspot.com/2010/06/quick-comment-facts-is-facts.html">http://moiramanion.blogspot.com/2010/06/quick-comment-facts-is-facts.html
I enjoy your blog, by the way, very much.

You are absolutely right - I was about 11 or 12 when I started wearing nylons with a belt (around 1966 or 1967) and I remember well when panythose came in almost immediately after that. That would distract me in a 50's story too. I think maybe only writers (me included) catch most of these things to nitpick though I hate when I read that a character's eyes are an amazing green, and a few chapters over they are suddenly plain gray...