after the trip.... what is your coolant/water level at? this will eliminate the possibility of it being your water pump. unless your pump is not leaking but is worn way out.
does it change/get lower when u get back... also chack and make sure your fans kick on and off, hondas take longer than most cars to heat up all the way...so on a short trip it wouldnt have time to heat up all the way... on a long trip it does...

check the levels of coolant before and after trip... check your fans and make sure they work