boiling trans fluid

Just took my first rip in my newly acquired 95 - it was great - comfortable, powerful, and fun. After about he first 125 milies the SES light came and and because of an earlier post I am was sure it was the turbine speed sensor. The next morning I checked all the fluid levels and found the trans fluid a little low. I put in some lucas, the light went out, and the shfiting was back to normal. ON the return trip it happened again so I stopped and checked the fluid levels. The trans fluid was not low, but it seemed to be "boiling". Is this normal. Should I put in a "cool trans" supplement? Before the trip I had the trans serviced iwth new filters and fluid.