During the defrost cycle the temperature gets to 50 degrees. It goes back down within 2-3 hours. There has never been a problem, but I worry about food spoilage.

Should I stop worrying?

That's not really a big problem, but the freezer fan should turn off while it's on defrost to keep warm air from entering the fresh food section. It should defrost in the middle of the night. To fix this wait until about 2 or 3 am then turn the defrost timer until it clicks off the refrigerator and starts defrosting. Problem solved!