i just installed my tranny temp gauge, i had some problems at first, wired it wrong

but now i got it all wired right and seems to me its not calibrated right. it sat all night and when i started it up in the mornin, ambient air was about 45 or so. the gauge read 100. drove about 10 minutes it was already to 150. Then it sat for about 5 hours and when i started it up it was at about 125, about 30 minutes or so town driving, a little highway, it was at 160 or so. Is something wrong or is this normal?