The battery may be going. Check the cranking voltage-- if it's less than 8V, it's the battery. The standing voltage should be 12.4V or higher and it should charge at 13.8-14V. At <1year old, the warranty should be good.
Starter? Probably a good time to remove it and do a service on it. Clean and lube, check brushes, replace the front shaft bushing. A lot of miles/years, then refurb the solenoid.
'73 R60/5 Toaster