Consider yourself lucky if you sent off your Motorola Xoom for the 4G LTE upgradeand got it back in about a week, as promised. It seems that Motorola Mobility is now having some trouble holding up their end of the bargain on the quick turnaround. In a note to eager, empty-handed slate faithful, the company informed those waiting that it's experiencing delays and will let customers know when their device finally ships. Surprised that an upgrade that requires you to actually mail in your tablet isn't being returned "on time?" Yeah, neither are we.