In my experience, the problem is not closely related to the wattage of lamp. Some lamps draw almost zero current until they strike, hence the ability to accumulate charge through the leakage of an SSR snubber.

Perhaps your 60W lamp will have a different ballast; opne which doesn't accumulate charge as your 10W ballast. Only testing will tell.

Unless a ballast/lamp is specifically marked to support solid state relays and/or dimmers, there is a remote possibility of overheating in addition to the undesired operation.