It should be fine with another coat unless there are areas where the water got underneath causing blistering. This takes an up close inspection and is remdied by pin-holing the blister to allow the water to escape and letting it dry. If you dont feel confident about the installers integrity, get an un-biased opinion from a friend or family member, or someone reputable that can do a thorough inspection.

sierraeast,
Thanks...that gives me hope that not all is lost!
Julia

elsastomeric should be applied when temps are at least 65 degrees.this information is on the bucket of elastomeric.
these products should be installed at correct temps and when there are no chance or rain.
you may have to wait and re-do when temps are higher and chances of rain are few.
usually one coat is installed mid morning (when dew is dried on roof) and the final coat in mid afternoon.
also elastomeric requires two coats applied in opposite directions. on a tin roof the first coat goes across ridges in tin, second coat goes in same direction as ridges.
post your pics, and read the install directions on the
container. your handyman should have read before installing.

best of luck