Recently I was visiting PVD airport and I remembered that the parking garage offered a good view of the southwest airlines gates. After about five minutes of shooting 737's at the gate while standing in the parking garage, I was approached by a security guard who informed me that photography in the garage was prohibited. I was unaware of any rules, in addition there are no signs anywhere indicating this rule. I checked their website, there is no rule listed anywhere that I can find. I was too nervous to ask about the rules as this was my first interaction with airport security.
Should I take the security guard's word for it?
Should I go back and ask about the rules if I am confronted again?