Perhaps he burned himself while trying to get more UVB or warmth.
If the distance to the UVB is too great or the temperature of the basking spot is too low, a cham will attempt to get as close to the source as he possibly can.
The best basking distance from a UVB bulb truly depends on which kind of bulb it is.
Some bulbs, like the long/linear fluorescent ReptiSun 5.0 only emit UVB effectively for up to about 1 foot, so your cham's basking spot should be located within 12" of the bulb..
Other types of bulbs, such as mercury vapor bulbs like the PowerSun are designed for the cham to be used much further away, so the basking spot must be adjusted to a greater distance from the bulb.
He may be trying to get warmer, as his basking spot temperature is lower than the 90-95 recommended for adult Veiled chams--though 85 is a good basking temp if he is a juvenile.
As for basking bulb distance, the goal is to provide the optimal basking spot temperature, which will depend on wattage and room temps, which will often vary throughout the year.
Here's an excellent forum caresheet with some more Veiled-specific information.
On the left side of the linked page are links to much more helpful info..
Hope this helps you out.
