If you do a "site:domain.com" operator and google is still showing results, then be happy - you're not de-indexed.
It could be that your website doesn't usually get too many backlinks to it, and then if you did 25 in one day it seems like a 'jump' to Google and perhaps they're deciding for a better placement of your site.
To be honest, if I were you (and I'm not SEO professional) if the site is established, I would keep on building those links. I really don't think it's good to do a jolt here and there every now and then, it really makes it not look organic. I mean, if google indexed all of those 25 backlinks in one day.... but all other days, there is nothing, it may not look so good to them.
That's why I try and build a couple of back links everyday. I am probably over doing it, but on fairly new sites (1 month old) I am building about 10 links a day to each of my 3-4 sites using my own auto approve list. I do this every day (or at worst, every second day) to keep the links looking natural, to give the impression that people are linking to my site everyday. I think this is the best way to go about it.
I think you'll be back in the results soon, well, I hope so at least !
Edit: Oh and also, make sure to vary your anchor text. 25 back links with the same anchor text makes it look suspicious, as I doubt 'people' would be linking to the same site with the same anchor EVERY time. Again, you probably know this, but I'm just saying. Also, link to internal sites too, not just your home page. Gotta keep it looking natural.
