In my group i have an unique problem....

My players develop gaming phobias...or they're learning i am not sure so here is an example..

for example:
they go tricked into huddling around this letter because they did not know what it said [it was in dwarven, and most were elves] and they convinced the dwarven fighter to read the letter.It was booby trapped with an Explosive rune spell... Now [in another campaign] they have some one [usually an Npc] read their letters and mail while casting comprehend languages to see if it was trapped and "wasting" detect magic on sheets of paper with writing on them.

am I being too critical of them... or do I need to tone down the subtle threats so that they become less paranoid...