Yes it is. Considered as bad as dumping oil or antifreeze.

The green tint is a dye that they put into the lubricating oil in the refrigerant so you can visually detect leaks. It glows under a blacklight.

As for your problem... There could be a problem with the compressor or a there is a pugged line and pressure is building up and the compressor is tripping out when it's overloaded.