Odd Occurance

SERPs flipped back to old title

[Khensu]

I usually hang out in Adsense but I had a question for here.

I updated my index page title a few days ago from:

"keyword keyword" & "keyword keyword", get Hundereds FREE!

to

"keyword keyword" & "keyword keyword", Download 500+ FREE!

It was up for two days and now it flipped back on all entries both Google and Yahoo.

Is that Bad?

Is there somthing wrong in the second title?

I have the same positions and everything else is fine.