Light smoke coming out of the hood while driving possible head gasket issue?

I had barely been driving any miles for the past 1+ year- sometimes once per 2-3 weeks. The car might sit for a week or more without being touched. 3 months ago, the battery began to fail- it took several attempts to turn over when cold. Then I noticed light smoke coming out of the hood while driving (and a few minutes after turning off) even though the engine temperature was perfect, and the engine was running fine. The battery was getting worse, so I took it to my mech. I told him about the starting problem but forgot to tell him about the smoke. I also told him how rarely I drive. He replaced the battery and told me that the car sitting drained the battery. He also told me I must drive at least 10 miles per week and run it at least twice per week. He also said he noticed the hood smoke, which he said meant I would need a new head gasket. I left, and immediately began driving at least 15-20 miles/week and drive at least twice/week never letting the car sit for more than 3 days. The smoke problem disappeared almost right away after starting this routine. It's been 3 months with no more smoke problem. Today I checked the inside of the oil cap- no residue of any kind. I removed the radiator cap and started the car- no bubbles at all, just perfect. Zero oil and coolant loss, no visible leaks. No warning lights and the engine just hums along perfectly and quietly. Order less Exhaust vapor when it's cold, which disappears after 2-3 miles. Compression feels great, power and acceleration are great. Do you think it's possible my mechanic mis-diagnosed the problem as head gasket based only on the smoke in the engine compartment? It was very busy that day- he was just finishing the new battery and clamp when I arrived. Thank you.