It's most likely the settings you used to save the PDFs in Illustrator, but it may not mean anythign at all. Normally ID doesn't list a resolution for PDF because they can be mixed.
I've checked the resolution in Photoshop just as a double-check and it shows resolution as 300 PPI. When you say "because they can be mixed" do you mean because elements and graphics with the PDF can be of varying resolutions? I hadn't thought of that, if that's what you meant. I do have some items within my pdf that might be lower resolution.
If these show up in my Preflight Panel as an issue, does this mean they would be flagged also with the Printer? In trying to find a resolution I read several forum discussions about how Printers often run your document through a Preflight process and will send it back when there are low resolution images in the document.
Is there some other way to be sure these images are in the InDesign document as 300 PPI so I can know they will in fact print correctly?
PS - Peter - thanks for the super quick response! And I saw your the highlighted "Exceptional Contributor" on the right sidebar for the InDesign forum - clearly well-deserved! Congrats
Yes, that's what I meant. Besides the ability to contain both raster and vector, you can have multiple images of varying resolution in a PDF.
I don't think I've ever seen a PDF show a resolution in the info panel, so I really don't have a clue. My guess would be as long as the raster content, presuming it's placed images in Illy, is at least 300 ppi at the size used, and you aren't downsampling there when you save as PDF it should be fine. Resolution for meshes and raster effects needn't be as high.
You could run the PDF through Preflight in Acrobat Pro, too, to get a report on the individual images.