Toyota Repair: Transmission and oil leak question, toyota tercel, pan gasket

Question
I own an 89 Toyota Tercel with 140000 miles .First question, all the years I owned the car whenever I changed the transmission fluid I just had the pan dropped and a new filter put in ,usually costing between $50 and $70.It has been 30,000 miles since I had it done and my mechanic advised doing a transmission flush ,BG ist he system, because it removes everything,It would cost around $150 with synthetic fluid,alittle less with regular.Is this necesarry on a car at this stage with the high milage and age? I do believe in preventive maitenance but wouldn't just dropping the pan and adding new fluid be satisfactory? I see these flushes have become the rage,engine,trans,cooling system.Also I recently had a major oil leak repaired,crank seal and oil pump seal.Cost $350 only because the oil was leaking onto the brake pads.Thus it failed state safety inspection .Now there is slight leaking from the oil pan gasket but it is only leaving maybe a couple of  dime size drips on the ground and I have only had to add a quart of oil in 2200 miles,it is soon due for an oil change,Is it reasonable to expect slight leaks on a car this age?I mean I could go crazy spending money tring to fix every little thing but I don't think it is worth it.

Answer
At this point I would just remove the pan and replace the gasket to stop the leak, it sounds like you maintained it well and if the fluid is not too discolored or dark the flush doesn't seem to be needed.
At this mileage you can expect some things to go wrong like small oil leaks but nothing major if the vehicle is well taken care of and all factory scheduled maintenance is done.