Did you ever get to the bottom of this? Just a few weeks ago I have a page with a table start doing a similar thing. The page allows me to select a row and open a view of just that record. This second page has the correct dates.
I have gone so far as to create a brand new page based on the same collection and have the same incorrect results. I now have 1000 records in the collection, but that shouldn’t have any impact on displaying the data correctly.