Three things about this issue which may simply be random quirks on Loeb's part, or may have some deeper significance:
1. When Buffy first sees Willow in her past-dream, she acts very surprised to see that Willow is alive and not evil. But Buffy knows she only killed the future Dark Willow, not "her" present-day Willow. Why is she so shocked at seeing Will alive?
2. When she returns from her dream, Present!Willow tells her, "Andrew called in and he's in Madrid again...the vamp nest looks bigger than they thought, again." And Buffy replies, "Why do you keep saying again?"
Now, there was reference way back in issue #1 to Andrew having to deal with a Spanish vamp nest that was bigger than they thought...but why would Willow (who wasn't around yet) know about that and Buffy (who was around) NOT know about it?
3. Buffy's dream covers the events of an entire day, but her friends tell her she only dropped off to sleep for a few seconds. While there is certainly time compression in dreams, usually you don't start dreaming the instant you fall asleep, and I don't think it's possible to dream a whole day, in detail, in 4 seconds.
So... is there some sort of subtle reality displacement going on here? Was this more than just a dream? Are the events of "Time of Your Life" starting to have their first slight noticeable effects on the time stream?
Because God knows, when Joss presents us with something that looks like innocent filler... it usually isn't.