Hi, Dan,
It's about the resolution (your 5000px X 4000px), not the file size. As long as your file is less than 25mb, has not been enlarged, is in sRGB or AdobeRGB color space, and is jpg or png format, you should be good to go.
(Hope I didn't forget anything.)
Best of luck! :-)
Edit -- I'll add that my own files range between 1.5mb and about 23/24mb. I always use .jpg in sRGB.