Let's do the maths!
9 V - 3.3 V = 5.7 V dropped over the LDO
0.1 W = I * 3.3 V -> I = 0.03 A through the laser module
P = 5.7 V * 0.03 A -> P = 0.171 W dissipated in the LDO (approximatey)
UPDATED P = 5.7 V * 0.1 A -> P = 0.57 W dissipated in the LDO (approximatey)
55 C/W junction to ambient -> 55 * 0.171 = 10 C above ambient for a TO-220
UPDATED 55 C/W junction to ambient -> 55 * 5.7 = 31 C above ambient for a TO-220
I would guess you're drawing power for more that just the laser module from the LDO or the laser module is consuming more than 100 mW. I realise i am assuming that input power equals output power for the laser but i think it'd need to be a factor of 2 or more out before it'd explain why it gets too hot to touch.
UPDATED The LDO should reach about 55C which i would consider quite hot to the touch as it's ~18 C above body temperature.