hey highclimb,
yes, deer ticks are the ones that transmit lyme disease, and they are small. however if the tick is attached long enough it can get quite large. the incubation period of lyme disease is pretty variable from a few days to a few weeks, so unless you develop symptoms there isn't much to do about it other than make sure you don't get a local skin infection at the bite site. probably the major determinant in whether you transmit the disease is the length of time the tick is attached, so checking early and often is very important. the majority of people will get the classic rash, a reddish ring that grows outward from the bite with clearing in the center, but its not 100% so if you have any concerns than you can go to your doctor and get a lyme titer test which will give you a definitive answer. lyme disease is easily treatable with a simple course of antibiotics and the sequelae are generally not permanent. you should be fine as long as you are not too much of a hypochondriac.
dr. jay