You don't "have" to monitor the temps, but allowing the bag to sit in the water for a while to help even out the temps is good. Also the pond pH might be a lot different than the hatchery water, so adding water to the bag in increasingly greater amounts to get the fish acclimated to the new water is always a good idea.
But, with that said, FH are pretty hardy, and doing what you did is what I do as long as the temps feel pretty close to the same. I've never used a thermometer to monitor temps, but Cecil did when we stocked trout in my pond. IIRC the temp difference was 3°F.
