Odd incident with sudden symptom

Patient: 3 days ago a vertical groove suddenly appeared on my fingernail after I pressed on a tiny tiny cyst on it’s cuticle. The cyst flattened out immediately. What could it mean? I’m 60 and in very good health.

Symptoms: Just that the groove is kind of deep. The fact that it was sudden has me worried that it may be a sign or symptom of something else.

Doctor: