I've lost mine for weeks at a time. The last time it was missing from October until just recently and it was in a purse I never use. Someone at home cleaned up by grabbing all of my belongings that were laying about and putting them in the purse before hanging it up in the closet, then forgot what they did.

It's already been de-activated but it was only a $20 pay as you go phone from virgin mobile so it's not a huge loss at least.