you bumped it after a half hour? wow...
No heat should be needed if you used the clear bathroom silocone. while still bolted to the truck, just pull towards you on the lense and it should come loose. but be careful...don't wanna break your plastic backing. try and clean out as much of the old silocone that you can, then reapply...this time better. I like to use bigger sized rubber bands to keep them together while the silocone cures and hardens. But your hands pushing the two pieces together for about 20 mins should do the trick just fine too.
'01 XLT disguised as a '03 Fx4 Level II
Big. Loud. Slow. Bright.