I didn't make it!
I had this same bug happen two days in a row now on Medivh.
I usually aim to finish my dailies shortly before the reset because it's less crowded. Any dailies I do in the hour before the reset claim to count toward my total for the current day, but after the reset message those dailies are not available again. Also, just like the OP said, my total available dailies for the new day are not 25, but 25 minus however many dailies I completed in the hour before the daily reset message. So today, for example, I had 19 dailies remaining right after the server claimed to reset them. I had this problem with the Netherwing dailies because they were the last ones I did.
Tentatively, I think this problem is different with the Sunwell dailies, oddly enough. A couple days ago I finished and turned in all the Sunwell dailies right before the reset except the bombing run, which I turned in after the reset. All the Sunwell dailies except for the bombing run were available again, as they should be.
However, my "available dailies remaining" count was not 25, but more like 20 or so. In other words, just like the Netherwing dailies it's as if it were subtracting the Sunwell dailies I did in the final hour from the new day's daily count. Unlike the Netherwing dailies, the Sunwell quests were still available again.
This sounds like it belongs in the WoW sub-forum.