We had a problem with mismatch between DS's reading level and his humor/interest level. He was not getting elementary school humor as a 3 year old. He sped through all 41 of the Magic Treehouse books and my collection of old Ruth Chews, but couldn't read Horrible Harry or the School of the Black Lagoon or Stink etc. because they were boring since he didn't get the jokes. (I asked the children's librarian for help after explaining and she looked at me like I was nuts and recommended Mo Willems Pigeon books, I'm like yeah, we own those.) He also likes big print and occasional pictures. At 4.5, magic books and non-fiction work really well, humor and mysteries not so much.
Happily Junie B. Jones didn't make it past the second chapter. He's currently on a non-fiction jag. If you can get the big old hardbacks of the Oz books with the original illustrations from the library, those are nice.
So no, I don't think it's a problem. Seek books at the right reading level with big print that are also the right interest level. Scholastic books has a nifty feature that lets you choose both RL and IL ages separately to recommend books.
