Several Warning Lights popping on at the same time

Hi all,

So I am receiving occasional warning lights that pop on all in one instance. Note: they seem to always come on during 20-40 minutes of highway/freeway driving.

In the digital readout:
1. Air Susp. Inactive
2. HDC Inactive

Icons on the dash:
1. ABS icon
2. Brake icon
3. Exclamation (!) point icon

Unfortunately I am unable to witness this occurrence because it seems to only happen when my parents drive my vehicle. I scoured the forums and it looks like it could be a number of things (steering angle sensor, low voltage from the battery, ABS issues). However the one thing that is throwing me off here is the Exclamation Point ( ! ) warning light icon. I found a possible answer here regarding the exclamation point: viewtopic.php?f=2&t=27863&p=214108&hilit=exclamation#p214108 -- however this light never came on during a turning of the wheel so hopefully it isn't directly related to an expensive air suspension bag.

Note: all lights go off and don't come back on (until the next unplanned occurrence) after the truck has been shut off and restarted.

Obviously I am HOPING it is as simple as resetting the steering angle sensor as I installed a fresh battery 4 months ago and was unaware of the reset procedure and thus the vehicle still has not technically had its steering angle reset since then.

Any other ideas I might have missed? In the meantime, I'm going to have someone reset the steering angle sensor today. Obviously trying to avoid going to the dealer although it may be inevitable if these warning lights don't stop "ding"ing at me.

Thanks in advance!