Full synthetic, semi-synthetic, mineral, all of them are fine.

You would want to worry if you had higher km's on the bike and wanted to switch to full synthetic since the full synthetic oils often have great detergent packages that scrub off all the deposits and sludge that may have been plugging leaks. Some have additives to swell rubber seals to help fight this. If you switched back to mineral later, the seals would shrink and you would often get worse oil leaks than you may have had before.

If you switch back and forth often, very little consequences, if any.