Temp sender position?

[El Campo]

Is it all right to have the temperature sender in the intake manifold or does it have to be in the head? Worried about my AFR's health and not excited about potentially warping them. I have had the sender in the intake manifold without problems but wondering if I am just lucky?? I fear that my other screwup has just been keeping me oblivious to it possibly actually heating up (I had Teflon tape on my sender threads before I read somewhere that this causes erroneous temperature readings).