Recently I increased the price up a little bit from $3.5 to $3.9, perhaps that's the reason because the customers paid the lower price previously than the current price tag. Maybe this is how from itch.io system work, the customers must paid same or higher price of the package/bundle in one transaction, to avoid any price tag increases in the future from the seller. For example if you bought a bundle for $10 and one of the package inside is $4 you still can download it because it passed the limit even though one of the package increased into $5 or $9 in the future. But if you only bought 1 package only with $3 (let say the original price) at that time and now the package price is $3.5 there is a chance you need to buy it again with the new price or higher. I know this is strange and this matter should bring into Itch.io
Please let me know if you remember, did you buy a bundle or just this package? how much did you bought at that time?
If this is unsolved in any way, could you share your email so that I can just send you the file?