Well, I am definitely not in the know on this stuff...beyond answers to questions I have posted here and what little bit I have read.
It is definitely possible that .8 is low for you...but it could be spot on. Most of what I have read is that 1.0 to 2.0 is optimal. Though, the official range is supposed to have dropped from what you have above to 0.3 - 3.0.
Having this result in conjunction with T4 and T3 would be helpful. Again, my understanding is...T4 is pretty much the storage state of the hormone. Once it is converted to T3 is when the magic starts.
A TSH in the lower end is not a problem, assuming that the others are not high or low.
If you think there is a problem, the web is full of potential symptoms.
For me, when I was mildly hypothyroid, I was more lethargic, was gaining weight and couldn't stop and had more mental fog (couldn't concentrate or remember things). Another set of symptooms if low body temp and feeling cold.
The opposite side, hyperthyroid, can elevate body temperature, result in weight-loss and, in my case, cause mild palpitations.
Hope this helps...