You mean it goes down to 1X when you turn on your phone? This frequently happens to me, too, though I'm in a 4G area. My only options are either to restart the phone, or to use an app like LTE OnOff to switch to 3G-only (in which case, it'll jump up from 1X to 3G, but as soon as I try to switch back to 4G mode, it goes right back down to 1X). Occasionally, if I wait a few hours and try to switch back to 4G, it'll finally pop on.
I'm curious to know if the Droid Charge and LG Revolution have this issue, as well, because I wonder if it's a problem with Verizon's network, or with the phone itself.
Not to be a pessimist, but if it's an issue with the Thunderbolts rather than the network, I don't expect this issue to ever be fixed, unfortunately. This seems like one of those little problems that'll never really be addressed or fixed, until it's time to upgrade to new phone anyway.