There has always been a limit.  Maybe your PDF are bigger than usual?

At any rate, your PDFs are very large and probably don't need to be that big.  You can change the quality/size in a PDF program (things like CutePDF and BullZip are free).  Or if you are scanning them, use lower quality scanning and don't use color.  I usually use 200dpi in Black and White and it works fine.