According to the manual you void your warranty if the tamper seals are broken. But frankly, this isn't clear at all to me without inspection. From manual:
Warranty is voided if:
1. "The tamper seal on the LaCie 2big or an individual Drive Bay casing is broken.
2. "One or two of the hard disks have been removed and replaced by any hard disk other than a drive provided by LaCie. For drive removal/replacement process, see section 4, Removing and Installing Drives"
So in effect, those tempting hard drive bays are trojans for Lacie mark-up. Figures.
But anyways, if this is indeed the case about the seals, I would be worried that they exchanged the drives for cheaper ones and your warranty is void, like your worried about. THis would suck badly. I would think a return to sender is perhaps your only option. Unless Lacie makes an exception. But you know how that goes. Anyway, There are some cheap 3.5" drives that somebody might have stuck in there.
It's funny, as I just made a few posts earlier today in a related thread about this drive, as I bought a refurb (for a good price also). I was worried about the same thing. I will want to make sure 'refurb' means 'restore to factory', and not 'degrade to sell cheap'. I paid over $300 and can not live with anything other than Apple level refurbishment.
Anandtech has a review for this drive and you can see Seagate Barracudas they use as the drives. I can understand why Lacie would put seals on these as they (justifiably) don't want anyone complicating warranties and tech support. But it does seem kind of silly as it's not like your opening anything-it's already opened.
so the bottom line is: post the answer here after you call lacie, please.