The bike just started doing this - every once in awhile when starting I hit the starter button, but it sounds like the starter is slipping or it is making noise but turning the engine over. Is that the starter going out, or the battery or what? Original starter with 26K miles. High compression 103" conversion (but it has electric compression releases). Battery just over one year old. Maybe the compression releases are intermittent and the starter can't turn it through a compression stroke????

 

Start with the simple stuff first. You can get your battery tested free at many auto shops, to confirm if that is OK. Check the high power connections in the starter circuit are all clean and tight, so the starter is getting max power.

The starter may indeed be slipping, as it has a small clutch inside it. The starter can be dismantled and cleaned and a new clutch installed for relatively little cost. Your bike is newer than mine, but with my 107" engine with automatic compressors the original starter started doing something similar. I have installed a higher output starter plus beefed up battery cables, just for insurance!