Question about iPhone texts?

So I had a question about the read recipes for an iPhone. It initially marked my text to him as read (like it should when the read recipts are enabled). After a while though, the same read text showed up as delivered.

Does this happen when read receipts are disabled or is it some kind of glitch?

This happened to me a while back also, it sounds more like a glitch and your best option is probably to restart your phone.