There sure is, and it is fairly easy to check. The ignition coil in these engines are very susceptible to heat. They can heat up and loose their ability to produce spark, cool off and begin to work again. Sometimes they start off working for an hour and eventually the run time will lessen until the engine just will not start anymore.
The easiest way to check this is with an in-line spark tester or an extra spark plug. If you purchase an in line spark tester, you can run it in line with your spark plug and coil and watch the spark through the window of the tester. If you don't want to invest in one, keep an extra spark plug handy. When your tractor dies remove the spark plug wire and hook it to the extra plug. Ground the threaded portion of the plug to a bare metal spot on the engine. Do not hold it!
Watch the spark plug, you should be getting a nice bright blue spark. If you don't then you most likely need a new coil. You can run this test when the engine is cold so that you have something to compare to when the engine is hot.