Weird, airbag light should not clear at all by itself once the airbag ECU has registered a fault. But these to lights do not have a shared connector at all (see page 37 in the wiring section of repair manual - if you don't have a copy, PM me).
And the bulbs are not next to each other in the cluster, but you might want to check the back of the cluster for anything that might cause shorts. But my best guess would still be the supply voltage.
How old are the battery and the alternator?