2001 Chevy Silverado hot transmission fluid

LS 4.8L light came on last month while going out of town driving on the freeway,i just pulled over for a few minutes and everything was find.i was not towing anything at all.when i come back i have it get a transmisson service done getting a machine to clean out all the fluid fulsh and cleaned which made the truck drive very smooth.this past weekend i go out of town and it happend to me twice that the light came on.what could be the problem that cause the transmission hot fluid to come on?is this the start of other problems like transmission going out.help me out thanks in advance.