I recently have been having a lot of air in my water... could a bad bladder in the expansion tank be causing this? The tank is only 18 months old and we have never had this prob before

could a bad bladder in the expansion tank be causing this?
No! A bladder tank will only expel what's put into it, (see image). The air in you line could come from several sources.
1) The water table could have dropped and you're sucking air **OR**
2) There could be a leak in the suction line that's pulling air in the line as the pump runs
Is there anything between the pump and your faucets such as a house filter or a water softener? Back to you, Tom